U.S. patent application number 11/685617 was filed with the patent office on 2008-09-18 for basal rate testing using frequent blood glucose input.
Invention is credited to Michael Blomquist, Thomas Alan Savard.
Application Number | 20080228056 11/685617 |
Document ID | / |
Family ID | 39708324 |
Filed Date | 2008-09-18 |
United States Patent
Application |
20080228056 |
Kind Code |
A1 |
Blomquist; Michael ; et
al. |
September 18, 2008 |
BASAL RATE TESTING USING FREQUENT BLOOD GLUCOSE INPUT
Abstract
An apparatus comprising a user interface configured to generate
an electrical signal to start a basal insulin rate test when
prompted by a user, an input configured to receive sampled blood
glucose data of a patient that is obtained during a specified time
duration, including a time duration during delivery of insulin
according to a specified basal insulin rate pattern, and a
controller communicatively coupled to the input and the user
interface. The controller includes an insulin calculation module
configured for determining at least one of an amount of basal
insulin over-delivered and an amount of basal insulin
under-delivered during the basal insulin rate test in trying to
meet a target blood glucose baseline. Other devices and methods are
disclosed.
Inventors: |
Blomquist; Michael; (Blaine,
MN) ; Savard; Thomas Alan; (Arden Hills, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Family ID: |
39708324 |
Appl. No.: |
11/685617 |
Filed: |
March 13, 2007 |
Current U.S.
Class: |
600/365 |
Current CPC
Class: |
A61M 5/1723 20130101;
A61M 2230/005 20130101; A61M 2005/14292 20130101; G16H 20/10
20180101; A61M 5/14244 20130101; A61B 5/14532 20130101; A61M
2230/201 20130101; A61M 2205/502 20130101; A61B 5/14503 20130101;
G16H 40/63 20180101; A61B 5/4839 20130101; A61M 2005/14208
20130101 |
Class at
Publication: |
600/365 |
International
Class: |
A61B 5/157 20060101
A61B005/157 |
Claims
1. An apparatus comprising: a user interface configured to generate
an electrical signal to start a basal insulin rate test when
prompted by a user; an input configured to receive sampled blood
glucose data of a patient that is obtained during a specified time
duration, including a time duration when insulin is delivered
according to a specified basal insulin rate pattern; and a
controller communicatively coupled to the input and the user
interface, the controller including an insulin calculation module,
wherein the insulin calculation module is configured to determine
at least one of an amount of basal insulin over-delivered and an
amount of basal insulin under-delivered during the basal insulin
rate test in trying to meet a target blood glucose baseline.
2. The apparatus of claim 1, wherein the insulin calculation module
is configured to determine the over-delivered amount and the
under-delivered amount using a correction factor of the patient and
a variance of a blood glucose level from the target blood glucose
baseline.
3. The apparatus of claim 2, wherein the insulin calculation module
is configured to determine the over-delivered amount and the
under-delivered amount using an adjusted correction factor of the
patient.
4. The apparatus of claim 2, wherein the insulin calculation module
is configured to determine a recommended change, if any, to the
basal insulin rate pattern.
5. The apparatus of claim 4, wherein the recommended change
precedes any actual time of over-delivery or under-delivery by a
time duration that compensates for a lag time associated with
subcutaneous insulin delivery.
6. The apparatus of claim 4, wherein the user interface includes a
display operatively coupled to the controller, and wherein the
controller is configured to display at least one user instruction
for the basal insulin rate test.
7. The apparatus of claim 6, wherein the controller is configured
to display a recommended change to a basal insulin rate
pattern.
8. The apparatus of claim 4, including: a pump mechanism configured
to deliver insulin according to the specified basal insulin rate
pattern; and a memory to store at least one basal insulin rate
pattern, wherein the pump mechanism and the memory are operatively
coupled to the controller.
9. The apparatus of claim 8, including a blood glucose monitor
communicatively coupled to the input.
10. The apparatus of claim 9, wherein the blood glucose monitor is
a continuous blood glucose monitor configured to automatically
collect the sampled blood glucose data.
11. The apparatus of claim 10, including: a display operatively
coupled to the controller, and wherein the controller is configured
to prompt the user, via the display, to begin a blood glucose
measurement using the blood glucose monitor.
12. The apparatus of claim 8, wherein the user interface and the
input are configured to receive the sampled blood glucose data
entered manually by the user.
13. The apparatus of claim 12, including: a display operatively
coupled to the controller, wherein the controller is configured to
display user instructions for the basal rate test, including
periodically prompting the user to enter a blood glucose value.
14. The apparatus of claim 8, wherein the insulin calculation
module is configured to determine an amount of active insulin in
the patient and to cancel the basal insulin rate test if the active
insulin amount is above a specified threshold insulin amount.
15. The apparatus of claim 8, wherein the controller is configured
to determine whether an insulin bolus dose is delivered and to
cancel the basal insulin rate test if it determines that an insulin
bolus dose is delivered during the basal insulin rate test.
16. The apparatus of claim 8, including a real time clock coupled
to the controller, wherein the controller is configured to vary a
basal rate of insulin delivery by a time of day according to the
basal rate pattern.
17. The apparatus of claim 4, wherein the input is a first input
and the apparatus further includes: a blood glucose sensor circuit
operatively coupled to the first input, the blood glucose sensor
circuit configured to produce a blood glucose signal representative
of a blood glucose level of the patient and provide the sampled
blood glucose data to the first input; a second input
communicatively coupled to the controller, wherein the second input
is configured to receive information related to insulin delivery
according to the basal rate pattern, and wherein the insulin
calculation module is configured to determine at least one of the
amount of basal insulin over-delivered and the amount of basal
insulin under-delivered using the insulin delivery information and
the sampled blood glucose data.
18. The apparatus of claim 17, including a communication port
communicatively coupled to the second input, the communication port
to receive the information related to insulin delivery.
19. The apparatus of claim 18, wherein the controller is configured
to communicate a recommended change to the basal rate pattern
through the communication port.
20. The apparatus of claim 17, wherein the user interface and the
second input are configured to receive the information related to
insulin delivery that is entered manually by the user.
21. The apparatus of claim 4, wherein the input includes a
communication port configured to receive the sampled blood glucose
data together with at least one time-stamp and to receive
time-stamped information related to insulin delivered according to
the basal rate pattern, and wherein the insulin calculation module
is configured to determine at least one of the amount of basal
insulin over-delivered or under-delivered using the time-stamped
sampled blood glucose data and the time-stamped information related
to delivered insulin.
22. The apparatus of claim 21, wherein the controller is configured
to communicate a recommended change to the basal rate pattern
through the communication port.
23. The apparatus of claim 1, wherein the insulin calculation
module is configured to calculate a lag time associated with
subcutaneous insulin delivery using at least one of: a type of
insulin; an activity level of the patient; a fitness level of the
patient; and the method used to obtain the blood glucose data.
24. The apparatus of claim 1, wherein the insulin calculation
module is configured to calculate a lag time associated with
subcutaneous insulin delivery using blood glucose data obtained
during at least one of a period prior to the basal rate test and a
period during the basal rate test.
25. The apparatus of claim 1, wherein the controller is configured
to cancel the basal insulin rate test if a blood glucose level of
the patient is outside of a specified range of blood glucose
level.
26. The apparatus of claim 1, including: a timer circuit; and a
display, wherein the timer circuit and the display are operatively
coupled to the controller, and wherein the controller is configured
to display user instructions for the basal insulin rate test at one
or more specified times during a day.
27. The apparatus of claim 26, wherein the controller is configured
to display user instructions for executing the basal insulin rate
test during a substantially same time on multiple days.
28. The apparatus of claim 26, wherein the insulin calculation
module is configured to: determine a time-varying basal insulin
rate function using the blood glucose data; and determine a
recommended change, if any, to the basal insulin rate pattern using
the time-varying basal insulin rate function.
29. The apparatus of claim 28, wherein the insulin calculation
module is configured to: determine a time-varying overnight basal
insulin rate function using the blood glucose data; and determine a
recommended change to an overnight basal insulin rate pattern using
the time-varying overnight basal insulin rate function.
30. A method comprising: receiving a user prompt in a blood glucose
(BG) management device to start a basal insulin rate test;
receiving sampled blood glucose data into the BG management device,
wherein the sampled blood glucose data is obtained during a
specified time duration, including a time duration when insulin is
delivered according to a specified basal insulin rate pattern; and
determining at least one of an amount of basal insulin
over-delivered and an amount of basal insulin under-delivered in
trying to meet a target blood glucose baseline during the basal
insulin rate test.
31. The method of claim 30, including automatically recommending a
change, if any, to the basal insulin rate pattern using the BG
management device.
32. The method of claim 31, wherein the recommended change to the
basal insulin rate pattern precedes any actual time of
over-delivery or under-delivery by a time duration that compensates
for a lag time associated with subcutaneous insulin delivery.
33. The method of claim 32, including calculating the lag time
using at least one of: a type of insulin; an activity level of the
patient; a fitness level of the patient; and whether the blood
glucose data was obtained from blood or from interstitial
fluid.
34. The method of claim 32, including calculating the lag time
using blood glucose data obtained during at least one of a period
prior to the basal rate test and a period during the basal rate
test.
35. The method of claim 31, including displaying at least one
instruction for the basal insulin rate test using the BG management
device.
36. The method of claim 31, wherein determining an amount
over-delivered and an under-delivered includes determining at least
one of an amount of basal insulin over-delivered and an amount of
basal insulin under-delivered using an adjusted correction factor
of the patient and a variance of a blood glucose level from the
target blood glucose baseline.
37. The method of claim 31, including delivering insulin according
to the specified basal insulin rate pattern using the BG management
device.
38. The method of claim 37, including: determining an amount of
active insulin in the patient prior to delivering basal insulin
according to the basal rate test; and canceling the basal insulin
rate test if an amount of active insulin is above a specified
threshold active insulin amount.
39. The method of claim 37, including canceling the basal insulin
rate test if an insulin bolus dose is delivered during the basal
insulin rate test.
40. The method of claim 37, wherein receiving sampled blood glucose
data includes automatically receiving the sampled blood glucose
data from a blood glucose monitor included in the BG management
device.
41. The method of claim 37, wherein receiving sampled blood glucose
data includes: obtaining the sampled blood glucose data using a
device separate from the BG management device; and receiving the
sampled blood glucose data into the BG management device from the
separate device through a communication port.
42. The method of claim 41, wherein receiving sampled blood glucose
data includes wirelessly receiving the sampled blood glucose data
into the BG management device from the separate device through a
wireless communication port.
43. The method of claim 41, wherein receiving sampled blood glucose
data includes periodically prompting a user through a user
interface of the BG management device to obtain blood glucose data
using the separate device.
44. The method of claim 41, wherein receiving sampled blood glucose
data includes receiving the sampled blood glucose data through a
user interface of the BG management device configured for manual
entry of blood glucose data.
45. The method of claim 41, wherein receiving sampled blood glucose
data includes prompting a user to manually enter a blood glucose
value during the basal insulin rate test.
46. The method of claim 31, including: delivering insulin according
to the specified basal insulin rate pattern using a second device;
wherein receiving sampled blood glucose data includes automatically
receiving the sampled blood glucose data from a blood glucose
monitor included in the BG management device; and wherein the
method includes receiving information related to insulin delivery,
including an amount of insulin delivered according to the basal
rate pattern, into the BG management device.
47. The method of claim 46, wherein receiving the information
related to insulin delivery includes receiving the information
related to insulin delivery from the second device through a
communication port.
48. The method of claim 47, including communicating a recommended
change to the basal insulin rate pattern to the second device using
the communication port.
49. The method of claim 46, wherein receiving the information
related to insulin delivery includes receiving the information
related to insulin delivery manually through a user interface on
the BG management device.
50. The method of claim 46, including displaying a recommended
change to the basal insulin rate pattern using the BG management
device.
51. The method of claim 31, including: delivering insulin according
to the specified basal insulin rate pattern using a second device;
receiving information related to insulin delivery, including the
amount of insulin delivered according to the basal rate pattern,
into the BG management device, wherein receiving sampled blood
glucose data includes receiving time-stamped sampled blood glucose
data into the BG management device; and determining the at least
one of the amount of basal insulin over-delivered and the amount of
basal insulin under-delivered using the time-stamped sampled blood
glucose data and the information related to insulin delivery.
52. The method of claim 31, including: determining a time varying
correction factor function using the sampled blood glucose data and
the specified basal rate pattern; and determining a time varying
basal rate pattern to achieve the target blood glucose baseline
using the correction factor function.
53. The method of claim 52, including recommending a change to the
specified basal rate pattern using the determined time varying
basal rate pattern.
54. An apparatus comprising: means for receiving a user prompt in a
blood glucose (BG) management device to start a basal insulin rate
test; means for receiving sampled blood glucose data of a patient
into a blood glucose (BG) management device, wherein the sampled
blood glucose data is obtained during a specified time duration,
including a time duration during delivery of insulin according to a
specified basal insulin rate pattern; and means for determining at
least one of an amount of basal insulin over-delivered and an
amount of basal insulin under-delivered in trying to meet a target
blood glucose baseline during the basal insulin rate test using the
BG management device.
Description
TECHNICAL FIELD
[0001] The field generally relates to patient insulin management
devices and, in particular, but not by way of limitation, to
systems, devices and methods for adjusting insulin therapy.
BACKGROUND
[0002] People who suffer from diabetes require insulin to keep
their blood glucose level as close as possible to normal levels. It
is essential for people with diabetes to manage their blood glucose
level to within a normal range. Complications from diabetes can
include heart disease (cardiovascular disease), blindness
(retinopathy), nerve damage (neuropathy), and kidney damage
(nephropathy). Insulin is a hormone that reduces the level of blood
glucose in the body. Normally, insulin is produced by beta cells in
the pancreas. In non-diabetic people, the beta cells release
insulin to satisfy two types of insulin needs. The first type is a
low-level of background insulin that is released throughout the
day. The second type is a quick release of a higher-level of
insulin in response to eating. Insulin therapy replaces or
supplements insulin produced by the pancreas.
[0003] Conventional insulin therapy typically involves one or two
injections a day. The low number of injections has the disadvantage
of allowing larger variations in a person's insulin levels. Some
people with diabetes manage their blood glucose level with multiple
daily injections (MDI). MDI may involve more than three injections
a day and four or more blood glucose tests a day. MDI offers better
control than conventional therapy. However, insulin injections are
inconvenient and require a diabetic person to track the insulin
doses, the amount of carbohydrates eaten, and their blood glucose
levels among other information critical to control.
[0004] Blood glucose (BG) management devices help a diabetic person
manage their blood glucose. For example, an insulin pump is a BG
management device that provides insulin throughout the day. A
glucose monitor (GM) or meter is a BG management device that
measures blood glucose levels. Some GMs require a finger-stick to
acquire a sample of blood that is applied to a test strip to get a
blood glucose reading. Some GMs are able to provide continuous
monitoring of blood glucose. Other BG management devices include
computers running software to help a diabetic person manage insulin
therapy. However, most BG management devices are limited in the
control over blood glucose that they offer.
SUMMARY
[0005] This document discusses, among other things, devices and
methods for managing insulin therapy. A device example includes a
user interface configured to generate an electrical signal to start
a basal insulin rate test when prompted by a user, an input
configured to receive sampled blood glucose data of a patient that
is obtained during a specified time duration, including a time
duration during delivery of insulin according to a specified basal
insulin rate pattern, and a controller communicatively coupled to
the input and the user interface. The controller includes an
insulin calculation module configured for determining at least one
of an amount of basal insulin over-delivered and an amount of basal
insulin under-delivered during the basal insulin rate test in
trying to meet a target blood glucose baseline.
[0006] A method example includes receiving a user prompt in a blood
glucose (BG) management device to start a basal insulin rate test,
receiving sampled blood glucose data that is obtained during a
specified duration of time when insulin is delivered according to a
specified basal insulin rate pattern, and determining at least one
of an amount of basal insulin over-delivered and an amount of basal
insulin under-delivered in trying to meet a target blood glucose
baseline during the basal insulin rate test using the BG management
device.
[0007] This summary is intended to provide an overview of the
subject matter of the present patent application. It is not
intended to provide an exclusive or exhaustive explanation of the
invention. The detailed description is included to provide further
information about the subject matter of the present patent
application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of portions of a BG management
device.
[0009] FIG. 2 shows example illustrations of a blood glucose
concentration graph and a basal rate pattern.
[0010] FIG. 3 is a block diagram of portions of an example of a BG
management device that includes a pump mechanism.
[0011] FIG. 4 is an illustration of a BG management device that
includes an insulin pump.
[0012] FIG. 5 is another block diagram of portions of a BG
management device that includes a pump mechanism.
[0013] FIG. 6 is a block diagram of a BG management device that
includes a blood glucose sensor circuit.
[0014] FIG. 7 is a block diagram of portions of another example of
a BG management device.
[0015] FIG. 8 is a flow diagram of a method of using a BG
management device to execute a basal rate test.
[0016] FIG. 9 is a flow diagram of another method of using a BG
management device to execute a basal rate test.
DETAILED DESCRIPTION
[0017] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and specific
embodiments in which the invention may be practiced are shown by
way of illustration. It is to be understood that other embodiments
may be used and structural or logical changes may be made without
departing from the scope of the present invention.
[0018] It is important for a diabetic person to be treated with the
proper amount of insulin. As discussed previously, high blood sugar
can lead to serious complications. Conversely, a person with low
blood sugar can develop hypoglycemia. Ideally, insulin therapy
mimics the way the body works. An insulin pump is one way to mimic
the body's insulin production. An insulin pump can provide a
background or basal infusion of insulin throughout the day and
provide a quick release or bolus of insulin when carbohydrates are
eaten. If a person develops high blood sugar, a correction bolus
can be delivered by the pump to correct it. While insulin pumps
improve convenience and flexibility for a diabetic person, they can
be sophisticated devices. Some insulin pumps can be difficult to
program. Proper use of an insulin pump requires a user to go
through a learning curve to properly use and program the pump.
[0019] Basal rate refers to a type of twenty-four hour background
infusion of insulin by an insulin pump that mimics the continuous
background release of insulin from a normal pancreas. It is the
rate of insulin delivery the patient normally needs independent of
the consumption of meals. The basal rate is typically specified in
insulin units per hour (u/hr). Typically, a basal rate for a pump
is initially programmed by a clinician based on a total daily dose
(TDD) of insulin for a diabetic person. The clinician may determine
TDD based on many factors including the type of diabetes of the
patient and the patient's weight, age, and level of fitness. The
amount of basal insulin is typically determined to be a percentage
of TDD, such as 40%, 50%, or 60% for example. The total daily dose
is then divided by 24 to obtain an average basal rate. For example,
if a patient's TDD is determined to be 40 units of insulin, and 50%
of the TDD is used for basal delivery, the average basal rate is 20
units/24 hours or 0.83 u/hr.
[0020] Many insulin pump users may use three or more different
basal rates during the course of a day. Basal rates can be adjusted
to change delivery every few minutes (e.g., 20-30 minutes) by
increments as small as 0.05 u/hr to better track changes in demand,
such as from an increase typically needed before dawn or a decrease
needed during long active periods. Insulin pump users may use
different basal rates for overnight, for breakfast to
mid-afternoon, and for mid-afternoon to bedtime. Appropriate basal
rates vary from person to person, may be different for a person at
various times of the day, and may change for a person over time.
Inappropriate basal rate settings may result in low blood glucose
levels overnight or high blood glucose levels in the morning. An
insulin pump user may go through several iterations of trial and
error before finding appropriate basal rates. Because a patient's
basal insulin needs may change over time, such as with weight
change or with a change in fitness level, basal rate testing may be
performed periodically to ensure that an appropriate basal rate is
being delivered by an insulin pump. Blood glucose (BG) management
devices are more valuable to a diabetic person if the device
conveniently assists them in determining their appropriate basal
rate or rates.
Apparatus Embodiments
[0021] FIG. 1 is a block diagram of portions of a BG management
device 100. Examples of a BG management device 100 include, among
other devices, an insulin pump, a blood glucose monitor (GM) or
meter, and a computing device running software to assist a diabetic
patient in managing insulin therapy. Examples of a computing device
include, among other things, a personal computer or a personal data
assistant (PDA).
[0022] The BG management device 100 includes a user interface 105,
an input 110, and a controller 115 communicatively coupled to the
input 110 and the user interface 105. The controller 115 can be
implemented using hardware circuits, firmware, software or any
combination of hardware, firmware and software. Examples, include a
microcontroller, a logical state machine, and a processor such as a
microprocessor, application specific integrated circuit (ASIC), or
other type of processor.
[0023] The user interface 105 generates an electrical signal to
begin a basal rate test when prompted by a user. The user interface
105 may include a pushbutton, keypad, or a computer mouse. The user
interface 105 may include a display operatively coupled to the
controller 115 to provide patient or user instructions for the
basal rate test. Examples of instructions include, among other
things, instructing the patient not to eat during the test, to
maintain a normal activity level, and not to administer an insulin
correction bolus during the test. The display may include a
touch-screen. The user of the device may be a clinician, caregiver,
or a diabetic patient. The user prompts the BG management device
100 using the user interface 105 to begin a basal rate test. The
basal rate test assists the user in determining one or more
appropriate basal rates.
[0024] As part of a basal rate test, the patient receives insulin
according to a specified basal rate pattern or profile. If the BG
management device 100 includes an insulin pump, the basal insulin
may be delivered using the BG management device 100. If the BG
management device 100 does not include an insulin pump, the basal
insulin may be delivered using a separate device that includes an
insulin pump.
[0025] If the BG management device 100 includes an insulin pump,
the BG management device 100 may further include a memory 116 to
store at least one basal rate pattern. The controller 115 may
display instructions for the user to enter one or more basal rates
to be delivered according to time of day. For example, the BG
management device 100 may allow the user to enter basal rate values
in 0.05 u/hr increments, and to enter time in increments of
one-half hour throughout the day. In some embodiments, the BG
management device 100 stores different basal rate patterns
according to different segments of the day, such as early in the
day, late in the day, and overnight for example. In some
embodiments, the input 110 may include a communication port and a
basal rate pattern may be loaded from a second device into memory
116.
[0026] The input 110 is configured to receive sampled blood glucose
data of the patient as part of the basal rate test. The blood
glucose data provides an indication of the concentration level of
the patient's blood sugar and the data may be obtained from blood
directly or from insterstitial fluid. The blood glucose data is
obtained during a specified time duration. The specified time
duration includes a time when insulin is delivered according to a
specified basal rate pattern, but may include a time prior or after
the delivery of insulin as well. The configuration of the input 110
may depend on the type of BG management device 100. If the BG
management device 100 is an insulin pump, the input 110 may be
coupled to a GM included in the pump or the input 110 may include a
communication port to receive the blood glucose data from a second
device. The second device may include a GM or the second device may
receive the blood glucose data from a third device. In some
embodiments, the input 110 is coupled to the user interface 105,
and the user may manually input the data into the pump through a
keypad or keyboard included in the user interface.
[0027] The controller 115 includes an insulin calculation module
120. Modules can be software, hardware, firmware or any combination
of software, hardware, and firmware. Multiple functions can be
performed in one or more modules. The insulin calculation module
120 determines at least one of an amount of basal insulin
over-delivered and an amount of basal insulin under-delivered
during the basal insulin rate test in trying to meet a target blood
glucose baseline.
[0028] FIG. 2 shows example illustrations (not real data) of a
blood glucose concentration graph 205 and a basal rate pattern 220
or profile during a basal rate test. Assume, as shown in the blood
glucose concentration graph 205, that the patient's target blood
glucose baseline 215 is 150 mg/dl (milligrams per deciliter) and
that this is the patient's blood glucose concentration level before
the basal rate test. Basal insulin is being delivered according to
a basal rate pattern 220. At time to, the user elects to begin a
basal rate test. User instructions for the basal rate test may be
provided. The blood glucose concentration is determined from blood
glucose data received into the input 110 during the basal rate
test. The basal rate test may run over several hours, e.g., six to
eight hours. In some embodiments, the blood glucose data may be
stored in memory for processing. In some embodiments, the blood
glucose data may be processed by the insulin calculation module 120
as it is received.
[0029] If the patient's blood glucose level remains at the target
blood glucose baseline 215 or within a specified range of the
target blood glucose baseline 215, the basal profile is
appropriate. If the patient's blood glucose level rises above the
target blood glucose baseline 215 or rises above a specified range
of the target blood glucose baseline 215, the basal rate is too low
and there was an under-delivery of basal insulin. If the patient's
blood glucose level falls below the target blood glucose baseline
215 or falls below a specified range of the target blood glucose
baseline 215, the basal rate is too high and there was an
over-delivery of basal insulin.
[0030] In the example in FIG. 2, the patient's blood glucose begins
to rise at time t.sub.3. The change in the blood glucose from the
baseline reaches 190 mg/dl, or an increase of 40 mg/dl. At time
t.sub.4, the basal rate pattern 220 includes an increase in basal
rate. The blood glucose level of the patient begins to change
direction, here a decrease, at time t.sub.5. The time duration from
the increase at t.sub.3 to the change in direction at t.sub.5 is
about two hours in this example. The blood glucose level of the
patient eventually falls to 110 mg/dl, or a total decrease of 80
mg/dl. At time t.sub.7, the blood glucose level of the patient
begins to again change direction. This time the change in direction
is an increase in blood glucose concentration. The time duration
from the decrease at t.sub.5 to the change in direction at t.sub.7
is about six hours.
[0031] In some embodiments, the insulin calculation module 120 is
configured to determine the over-delivered amount or the
under-delivered amount of basal insulin using a correction factor
of the patient and a variance of a blood glucose level from the
target blood glucose baseline 215. A correction factor refers to
the amount of drop in blood glucose concentration of the patient
for one unit of insulin. In FIG. 2, the 40 mg/dl increase
corresponds to an under-delivery of basal insulin. The
under-delivery may be due to the basal rate being too low or due to
an increased demand from the patient during that time of day. The
80 mg/dl decrease corresponds to an over-delivery of basal
insulin.
[0032] To calculate the amount under-delivered, the insulin
calculation module 120 divides the increase in blood glucose level
(+40 mg/dl) by the correction factor of the patient to determine
the amount of insulin required to lower the blood glucose level to
the target blood glucose baseline 215. This is the amount of
insulin that was under-delivered to the patient during the basal
rate test. Assume in the example of FIG. 2 that the patient's
correction factor is one unit per 40 mg/dl. In this case, a
correction bolus of one unit of insulin would decrease the
patient's blood glucose level to the blood glucose baseline. To
calculate the amount of insulin over-delivered, the insulin
calculation module 120 divides the decrease in blood glucose level
(-80 mg/dl) by the correction factor of the patient (1 u per 40
mg/dl). This corresponds to a correction bolus of -2 units of
insulin, i.e., the amount of insulin delivered needs to be reduced
by 2 units of insulin.
[0033] The under-delivered or over-delivered amount can be used to
recommend changes to the basal rate pattern. In the example of FIG.
2, the insulin calculation module 120 may determine that the
existing basal rate pattern 220 needs to be increased at some point
by one unit of insulin to address the 40 mg/dl increase and
decreased at some point by 2 units of insulin to address the 80
mg/dl decrease.
[0034] The BG management device 100 is more valuable if recommended
changes anticipate an under-delivery or over-delivery. However,
anticipating when to change the basal rate is complicated by a
delay, or a lag time, in insulin uptake before the insulin becomes
effective. Another complication is that the lag time may be
different for glucose levels measured using blood and glucose
levels measured using interstitial fluid. Measuring blood glucose
concentration using the interstitial fluid may make the uptake
appear to have additional lag time. In some embodiments, the
insulin calculation module 120 recommends a change in a basal rate
that precedes any actual times of under-delivery or over-delivery
by a time duration that compensates for a lag time associated with
the subcutaneous insulin delivery and with the glucose measurement
method.
[0035] In some embodiments, in addition to the uptake lag time, the
insulin calculation module 120 uses the time from a beginning of a
change in the blood glucose level to a change in direction of the
blood glucose data values to determine a recommended change to the
basal insulin rate pattern 220. In the example of FIG. 2, it is
determined that one unit of insulin is needed to correct the
under-delivery of insulin resulting in the 40 mg/dl increase in
blood glucose level. The increase began at t.sub.3 and a change in
direction occurred two hours later at t.sub.5. The insulin
calculation module 120 may recommend a change that includes adding
one unit of insulin to the basal rate pattern 220 and spreading the
delivery out over two hours corresponding to the change in
direction time, i.e., a rate of 0.5 u/hr. This shown by the basal
rate increase 225 of 0.5 u/hr for two hours over time t.sub.1 to
t.sub.2. The time t.sub.1 is shifted earlier than the time of the
increase at t.sub.3 by a time duration to compensate for a delay in
the insulin uptake so that the insulin may act on the blood
glucose.
[0036] Also in FIG. 2, an over-delivery of 2 units of insulin
resulted in an 80 mg/dl increase in blood glucose level. The
decrease began at t.sub.5 and a change in direction occurred six
hours later at t.sub.7. The insulin calculation module 120 may
recommend a change that includes subtracting two units of insulin
from the basal rate pattern 220 over six hours at a rate of 0.33
u/hr. This shown by the basal rate decrease 230 of 0.33 u/hr for
six hours over time t.sub.2 to t.sub.6. The time t.sub.2 is early
enough to compensate for the delay in insulin uptake.
[0037] The lag time for insulin uptake may depend on several
factors. In some embodiments, the insulin calculation module 120
determines a time duration to compensate for such a time lag using
the type of insulin delivered. Some insulin types have a faster
uptake than other types, and the insulin calculation module 120 may
use a table stored in a memory of the BG management device to
correlate a time duration to an insulin type. In some embodiments,
the insulin calculation module 120 calculates the compensating time
duration using an activity level of the patient and/or the fitness
level of the patient. In some embodiments, the compensating time
lag is pre-determined from clinical studies and is stored in a
memory for use by the insulin calculation module 120.
[0038] In some embodiments, the insulin calculation module 120 may
adjust the correction factor before determining an amount of
insulin under or over-delivered. In certain embodiments, the
insulin calculation module 120 may use a correction factor
multiplier to adjust the correction factor when determining the
amount of insulin under or over-delivered, and consequently
adjusting the amount of insulin in any recommended changes to the
basal rate pattern 220. For example, assume as in FIG. 2 that the
patient's correction factor is one unit per 40 mg/dl. If the
correction factor multiplier is 1.3, the insulin calculation module
uses a correction factor of one unit per 52 mg/dl [(1.3)(40
mg/dl/unit)]. For the 40 mg/dl increase in FIG. 2, the insulin
calculation module 120 divides the increase in blood glucose level
(40 mg/dl) by the correction factor of the patient (1 u per 52
mg/dl). This corresponds to a correction bolus of 0.77 units
[(40)/(52)] of insulin. The insulin calculation module 120 may
recommend adding 0.39 u/hr for two hours to the basal rate
pattern.
[0039] Using a correction factor multiplier results in a lower
amount of basal insulin allowing adjustments to be made more safely
made. This may give a user more confidence in using the recommended
changes to the basal rate pattern 220. The 80 mg/dl decrease
corresponds to a correction bolus of 1.54 units of insulin. The
insulin calculation module 120 may recommend subtracting 0.26 u/hr
for six hours to the basal rate pattern. The controller 115 may
store the correction factor multiplier in a memory. The correction
factor multiplier may be manually set or programmed by a clinician.
The clinician may set the correction factor multiplier to a value
that accords to a level of confidence or comfort to the clinician
in the recommended changes to the basal rate pattern 220.
[0040] In some embodiments, if the blood glucose data received
during the basal rate test indicates that the blood glucose level
of the patient is outside of a specified range of blood glucose
levels, the controller 115 cancels the basal insulin rate test. If
the blood glucose level is above the range, the controller 115 may
recommend a correction bolus to be taken by the patient. The
insulin calculation module 120 calculates the amount of insulin in
the correction bolus by dividing the blood glucose concentration by
the specified correction factor for the patient.
[0041] If the blood glucose level is below the range, the
controller 115 may recommend an amount of carbohydrates to be eaten
by the patient. The insulin calculation module 120 calculates the
amount of carbohydrates using a correction factor specified for the
patient and a carbohydrate ratio specified for the patient. A
carbohydrate ratio refers to the amount of carbohydrates reduced,
or covered, by a unit of insulin.
[0042] For example, assume that at the beginning of a basal rate
test, the blood glucose level of a patient is 40 mg/dl below the
specified range and the specified correction factor is 1 unit per
80 mg/dl. The insulin calculation module 120 determines that -0.5
units of insulin (-40/80) are required to bring the blood glucose
level back within the specified range. Negative insulin cannot be
delivered so this corresponds to a requirement for carbohydrates.
Assume that the carbohydrate ratio of the patient is 20 grams of
carbohydrates per unit of insulin (20 g/u). The insulin calculation
module 120 multiplies the amount of insulin by the carbohydrate
ratio to determine that the patient should eat 10 grams of
carbohydrates [(0.5)(20)]. The insulin calculation module 120 may
take into account additional factors such as the health status of
the patient and the activity level of the patient in recommending
the carbohydrate amount. In some embodiments, if the blood glucose
of the patient is outside the specified range of blood glucose
levels, the controller 115 suspends the start of the basal insulin
rate test until the blood glucose of the patient is within the
specified range of blood glucose levels.
[0043] As discussed previously, appropriate basal rates may differ
for a patient throughout the course of a day. The BG management
device 100 may include a timer circuit 117 operatively coupled to
the controller 115. The controller 115 displays user instructions
to execute a basal rate test at one or more specified times during
a day. In some embodiments, controller 115 displays user
instructions to run the basal insulin rate test on multiple days.
The controller 115 may prompt the user to run the test during
substantially the same time on the multiple days. This may result
in more appropriate basal delivery rates being used at different
times during the day.
[0044] It is often difficult to maintain a stable blood glucose
target value overnight because the correction factor varies as a
function of time. In order to stabilize the glucose value at a
target blood glucose value, the basal rate may often be adjusted
during overnight periods to compensate for changes in the
correction factor. An insulin pump user may go through several
iterations of trial and error while attempting to find appropriate
overnight basal rates. A trial and error method may result in less
than optimal control of overnight blood glucose level.
[0045] According to some embodiments, the BG management device 100
automatically executes a basal rate test during a period when food
intake is restricted, such as overnight for example. The basal rate
test may start a specified time after a user prompts the BG
management device 100 to execute the basal rate test. For example,
if the period is overnight, the user prompt may start a timer
circuit and the controller 115 may initiate the overnight basal
rate test when a time duration expires. The insulin calculation
module 120 automatically determines one or more basal rates for a
basal rate profile using a basal rate calibration and verification
technique. The basal blood glucose value g can be approximated
by
g(t).apprxeq.c(t)b(t-.tau.), (1)
where c(t) is the basal correction factor, b(t) is the basal
insulin rate, and .tau. is the delay or lag time associated with
the uptake of a subcutaneous infusion of insulin. Food consumption
and exercise are assumed to be negligible during the period of the
test.
[0046] The insulin calculation module 120 may perform a rapid
calibration that can be executed during a period as short as two
time periods, such as two nights for example. The correction factor
c(t) may vary as a function of time. To determine c(t), blood
glucose data values g.sub.1(t) and basal insulin delivery rates
b.sub.1(t) are recorded periodically throughout a first observation
period. Rewriting Equation (1) to solve for c(t) for the first
period yields
c 1 ( t ) = g 1 ( t ) b 1 ( t - .tau. 1 ) . ( 2 ) ##EQU00001##
The delay for insulin uptake .tau..sub.1 can be an assumed value
based on current estimates from clinical studies that use that type
of insulin, or can be determined on a per patient basis using
stochastic or deterministic time series analysis of prior or
current basal test data. The time series analysis of the blood
glucose data values may be performed under pulse function, step
function, or continuous changes in insulin delivery. The
time-dependent changes in insulin delivery may be present in the
user's current basal profile or the user may be prompted to create
a time-dependent change by the insulin calculation module. The
stochastic or deterministic time series analysis can be performed
on blood glucose data obtained from previous calibration or
observation periods, such as previous nights for example. Thus, the
delay for insulin uptake may be determined using blood glucose data
obtained prior to the basal rate test.
[0047] A desired target blood glucose value g.sub.t(t) may be a
constant or a function of time. Equation (1) can be written as
g.sub.t(t).apprxeq.c.sub.1(t)b.sub.1(t-.tau..sub.1), (3)
where c.sub.1(t) is the correction factor determined from the first
period of data values from Equation (2). Solving equation (3) for a
controlling basal insulin rate b.sub.t(t) that achieves the desired
g.sub.t(t) yields
b t ( t ) = g t ( t + .tau. 1 ) c 1 ( t + .tau. 1 ) . ( 4 )
##EQU00002##
It is assumed that the correction factor c(t) is a periodic
function that repeats on a twenty four hour cycle, and that c(t)
determined from data and basal rates during the first period of
reduced food intake will be similar on subsequent periods
twenty-four hours later.
[0048] During the second period of observation, blood glucose data
values g.sub.2(t) and basal rates b.sub.2(t) are again recorded
periodically. Ideally g.sub.2(t)=g.sub.t(t), but in reality
g.sub.2(t)=g.sub.t(t)+.epsilon.(t), where .epsilon.(t) is the
residual deviation from the target blood glucose value. Thus,
Equation (1) can be written as
g.sub.t(t)+.epsilon.(t)=c.sub.1(t)b.sub.1(t-.tau..sub.1). (5)
Assuming that .epsilon.(t) is primarily due to the error in the
estimate of .tau..sub.1, Equation (5) can be rewritten as
g.sub.t(t)+.epsilon.(t)=c.sub.1(t)b.sub.t1(t-(.tau..sub.1-.tau.)),
(6)
where .tau. is the error in the delay estimate. Combining Equations
5 and 6 gives
.epsilon.(t)=c.sub.1(t)[b.sub.t(t-.tau..sub.1)-b.sub.t(t-(.tau..sub.1-.t-
au.))]. (7)
Curve fitting or other standard minimization techniques can be used
to determine the most appropriate estimate of .tau. to satisfy
Equation (7). Once .tau. is determined, the control estimate for
the basal insulin delivery rate or rates b.sub.t(t) that achieves
the desired blood glucose target g.sub.t(t) can be written as
b t ( t ) = g t ( t + .tau. 2 ) c 1 ( t + .tau. 2 ) , ( 8 )
##EQU00003##
where .tau..sub.2=.tau..sub.1-.tau.. The insulin calculation module
may then recommend changes to the t basal rate pattern using
b.sub.t(t).
[0049] The rapid calibration technique is a method to quickly
achieve improved control over blood glucose level. In some
embodiments, the insulin calculation module 120 executes a basal
rate test that uses a generalized calibration technique to achieve
more accurate estimates of b.sub.t(t). The generalized calibration
method uses least squares estimation techniques with at least two
periods of observing blood glucose data and basal insulin delivery
rates. Referring back to Equation (1) and with g(t) and b(t)
measured over several periods, .tau. and c(t) can be estimated by
curve fitting with a finite order polynomial or an orthogonal
series approximation such as a Fourier series approximation for
example. The resulting estimate of b.sub.t(t) is calculated using
Equation 3 with .tau. and c(t) estimated from the curve fit
results.
[0050] According to some embodiments, the BG management device
includes an insulin pump. FIG. 3 is a block diagram of portions of
an example of a BG management device 300 that includes a pump
mechanism 330 to deliver insulin to the patient. The pump mechanism
330 is operatively coupled to the controller 115. The controller
115 may track the amount of insulin delivered via the pump
mechanism 330. The BG management device 300 includes a memory 116
operatively coupled to the controller 115 to store one or more
basal rate patterns 325. The BG management device delivers basal
insulin according to the basal rate patterns. The BG management
device 300 also may deliver insulin through boluses such as a
correction bolus or a carbohydrate bolus. In some embodiments, the
BG management device 300 has a timer circuit 117 that includes a
real time clock coupled to the controller 115. The controller 115
is configured to vary a basal rate of insulin delivery by a time of
day according to a basal rate pattern.
[0051] In some embodiments, the insulin calculation module 120 is
able to keep track of the amount of active insulin in the patient.
This is sometimes referred to as insulin on board (IOB). To track
the amount of active insulin, the controller 115 uses the amount of
insulin delivered, the time that elapsed since delivery of insulin
and a duration of how long the insulin is active in the blood. The
duration may be determined using kinetic action, which is the time
it takes for insulin to disappear from the blood, or the duration
of insulin action (DIA), which is how long the insulin lowers blood
glucose. In some embodiments, the controller 115 cancels a basal
rate test if the insulin calculation module 120 determines that the
active insulin amount is above a specified threshold insulin
amount. This minimizes the risk of IOB confounding the results of
the basal rate test.
[0052] In some embodiments, the controller 115 cancels the basal
insulin rate test if the controller 115 determines that an insulin
bolus dose, such as a correction insulin bolus or a carbohydrate
insulin bolus, is delivered during the basal insulin rate test. In
some embodiments, if the user enables an insulin bolus delivery,
the controller 115 displays a warning that the basal insulin test
will be canceled if the user elects to proceed with delivery of the
insulin bolus dose.
[0053] FIG. 4 is an illustration of a BG management device 400 that
includes an insulin pump. The BG management device 400 includes a
cassette or cartridge of insulin and tubing 440 connectable to a
patient such as by a Luer lock 445. The BG management device 400
includes a user interface that may include a display 402
operatively coupled to a controller 115. The user interface may
also include one or more keys 404.
[0054] Returning to FIG. 3, the blood glucose data obtained during
the basal insulin rate test may be produced by a second device
separate from the BG management device 300. The controller 115
displays user instructions for the basal rate test. The user
interface 105 and the input 110 are configured to receive the
sampled blood glucose data entered manually by the user through the
user interface 105. The controller 115 may periodically prompt the
user to enter a blood glucose value at different times during the
test, or to enter the blood glucose data all at once after the
test.
[0055] FIG. 5 is another block diagram of portions of a BG
management device 500 that includes a pump mechanism 530 and
delivers basal insulin according to one or more basal rate patterns
525 stored in memory 116. A blood glucose monitor, or GM 550, is
communicatively coupled to the input 110. The input 110 is
configured to receive the sampled blood glucose data from the GM
550. In some examples, the GM 550 is included in the BG management
device 500 and is coupled to the input 110. In some examples, the
GM 550 is included in a second device. The input 110 may receive
the blood glucose data during the basal rate test or after the test
is run. The input 110 may include a communication port, such as
communication port 447 located on the rear face of the device in
FIG. 4, and the GM 550 is communicatively coupled to the input 110
by the communication port 447. In some embodiments, the
communication port 447 is a wired port such as a serial interface
or bus interface for communicating with the second device. In some
embodiments, the communication port 447 is a wireless port such as
an infrared (IR) communication port or a radio frequency (RF)
communication port. The input 110 wirelessly receives the sampled
blood glucose data from the second device.
[0056] Returning to FIG. 5, in some embodiments, the GM 550 is a
continuous GM and automatically collects the sampled blood glucose
data. For example, the GM 550 may include a blood glucose sensor.
The blood glucose sensor produces a blood glucose signal
representative of a blood glucose level of the patient. The GM 550
samples the blood glucose signal to obtain the sampled blood
glucose data
[0057] In some embodiments, the GM 550 may need to prompt the user
to begin a blood glucose measurement. For example, the GM 550 may
require diabetes test strips to take a blood glucose measurement.
The controller 115 prompts the user, via a display, to begin a
blood glucose measurement using the GM 550. The user then provides
a new test strip to the GM 550 when prompted during the basal rate
test. In another example, the GM 550 may include a drum of diabetes
test strips and the user advances the drum to a fresh or unused
test strip when prompted by the controller 115. The controller 115
may display a recommended basal rate after the basal rate test. The
controller 115 may also communicate a recommended change in the
basal rate to the second device via a communication port.
[0058] According to some embodiments, the BG management device is a
GM. FIG. 6 is a block diagram of a BG management device 600 that
includes a blood glucose sensor circuit 635 operatively coupled to
the input 110. The blood glucose sensor circuit 635 produces a
blood glucose signal representative of a blood glucose level of the
patient and provides the sampled blood glucose data to input 110.
In some embodiments, the blood glucose sensor circuit 635 includes
an implantable blood glucose sensor. In some embodiments, the blood
glucose sensor includes a percutaneous blood glucose sensor. The
blood glucose sensor circuit 635 may include signal conditioning
circuits, such as for signal filtering and signal amplification for
example. If an implantable blood glucose sensor is used, the blood
glucose sensor circuit 635 may include a communication circuit
configured to receive blood glucose data wirelessly, such as by RF
communication.
[0059] The BG management device 600 includes a second input 630
communicatively coupled to the controller 115. The second input 630
receives information related to basal insulin delivery, such as one
or more basal rate patterns used during the basal rate test. The
information related to insulin delivery may be received into a
memory 116. The insulin calculation module 120 determines at least
one of an amount of insulin over-delivered and an amount of insulin
under-delivered during the basal rate test using the insulin
delivery information and the sampled blood glucose data. The BG
management device 600 may include a communication port 647 coupled
to the second input 630. The communication port 647 receives the
information related to insulin delivery from a second device. In
some embodiments, the communication port 647 is a wired port such a
serial interface or bus interface. In some embodiments, the
communication port 647 is a wireless port such as an infrared (IR)
communication port or a radio frequency (RF) communication port.
The second input 630 wirelessly receives the insulin delivery data
from the second device. As an example, the second device may be an
insulin pump. The insulin calculation module 120 may determine
changes to the basal rate pattern used to deliver basal insulin
during the basal rate test. The controller 115 communicates
recommended changes through the communication port 647 or may
display the recommended changes on a display.
[0060] In some embodiments, the user interface 105 and the second
input 630 are configured to receive the information related to
insulin delivery by a user manually entering the information
through the user interface 105. The insulin delivery information
may be obtained from a pump for example. The controller 115 may
display any recommended changes to the basal rate pattern.
[0061] FIG. 7 is a block diagram of portions of another example of
a BG management device 700. BG management device 700 includes
neither a GM nor an insulin pump. The BG management device 700
includes a user interface 105, an input 110, and a controller 115
communicatively coupled to the input 110 and the user interface
105. The input 110 includes at least one communication port 747
configured for receiving sampled blood glucose information. The
communication port 747 may provide a wired connection to a second
device, or the communication port 747 may provide a wireless
connection to a second device. The sampled blood glucose
information may include at least one time-stamp in order to align
the sampled blood glucose information to information related to
insulin delivery.
[0062] The insulin delivery information may be received through the
same communication port 747 or a second communication port. The
communication ports may be any combination of wired or wireless
communication ports. The insulin delivery information includes
information related to basal insulin delivered according to a basal
rate pattern, and may include at least one time-stamp to align the
insulin delivery information with the blood glucose information.
The insulin calculation module 120 determines at least one of an
amount of insulin over-delivered and an amount of insulin
under-delivered during the basal rate test using the insulin
delivery information and the sampled blood glucose data. The
insulin calculation module 120 may recommend changes to the basal
rate pattern. The controller 115 may communicate recommended
changes to the basal rate pattern through the communication port
747 and/or the controller 115 may display the recommended
changes.
Method Embodiments
[0063] FIG. 8 is a flow diagram of a method 800 of using a BG
management device to execute a basal rate test. At block 805, a
user prompt is received in a BG management device to start a basal
insulin rate test. The user interface may include a push-button,
keypad, or mouse. The user interface may also include a display to
display one or more instructions for the user to execute the basal
rate test, and to display to display any recommend changes to a
basal rate or a basal rate pattern. In some embodiments, the method
800 includes displaying instructions for the basal insulin rate
test using the BG management device.
[0064] At block 810, sampled blood glucose data is received in the
BG management device. The blood glucose data is obtained from a
patient during a specified time duration, including a time during
delivery of insulin according to a basal insulin rate pattern that
is part of the basal rate test.
[0065] At block 815, at least one of an amount of basal insulin
over-delivered or an amount of basal insulin under-delivered is
determined. The over-delivery and/or under-delivery occur in trying
to meet a target blood glucose baseline during the basal insulin
rate test. In some embodiments, the method 800 includes the BG
management device automatically recommending changes, if any, to
the basal insulin rate pattern.
[0066] In some embodiments, the method 800 includes determining an
amount of basal insulin over-delivered or an amount of basal
insulin under-delivered using the correction factor and the
variance from the blood glucose baseline concentration. In some
embodiments, the amount of insulin over or under-delivered is
determined using an adjusted correction factor. The correction
factor may be adjusted using a correction factor multiplier. In
some embodiments, recommending a change may include spreading out
the change to the basal delivery rate pattern out over a time
duration corresponding to a time to a change in direction of the
blood glucose data values.
[0067] In some embodiments, the method includes recommending
changes to the basal insulin rate pattern that precede any actual
times of over-delivery or under-delivery by a time duration that
compensates for a delay or lag time associated with subcutaneous
insulin delivery. In some embodiments, the method 800 includes
calculating the lag time using at least one of i) the type of
insulin delivered during the basal rate test, ii) the activity
level of the patient at the time the basal rate test takes place,
iii) the fitness level of the patient, and iv) the method of
obtaining the blood glucose data, e.g., whether the blood glucose
data was obtained from blood or from interstitial fluid. In some
embodiments, the method 800 includes calculating the lag time using
blood glucose data obtained prior to the basal insulin rate
test.
[0068] According to some embodiments, the BG management device
includes an insulin pump. The method 800 includes determining an
amount of active insulin (IOB) at the beginning of the basal rate
test. The IOB may be determined before delivering basal insulin
according to a basal rate pattern of the basal insulin test. In
some embodiments, if an amount of active insulin is above a
specified threshold active insulin amount, the BG management device
may cancel the basal rate test. In some embodiments, the method 800
includes canceling the basal insulin rate test if an insulin bolus
dose, such as a correction bolus or a carbohydrate bolus, is
delivered during the basal insulin rate test.
[0069] According to some embodiments, the BG management device
includes an insulin pump and a GM. The method 800 includes
automatically receiving the sampled blood glucose data from the
blood glucose monitor. In some embodiments, the BG management
device includes the insulin pump and the blood glucose data is
obtained using a separate device. The method 800 includes receiving
the sampled blood glucose data into the BG management device from
the separate device through a communication port. The communication
port may be a wireless port or a wired port. The separate device
may be a continuous GM.
[0070] In some embodiments, the separate device may be a GM that
requires some action by the user to obtain a blood glucose reading.
For example, the GM may require the user to place a test strip into
the GM in order to obtain a glucose reading. In some embodiments,
the method 800 may include prompting the user through a user
interface to obtain blood glucose data using the separate device.
The prompting may be periodic during the basal rate test.
[0071] In some embodiments, the blood glucose data obtained from
the separate device is entered manually into the BG management
device. The method 800 includes the BG management device receiving
the blood glucose data through the user interface. The user
interface is configured for manual entry of blood glucose data,
such as by including a keypad and a display. The user reads the
blood glucose data from the separate GM and manually enters the
blood glucose data into the BG management device. In some
embodiments, the method 800 includes the BG management device
periodically prompting the user to manually enter a blood glucose
value during the basal rate test.
[0072] According to some embodiments, the BG management device
includes a GM and does not include an insulin pump. The basal
insulin is delivered according to a basal rate pattern using a
second separate device. The sampled blood glucose data is received
automatically using the included GM. The method 800 further
includes receiving information related to insulin delivery into the
BG management device from the separate device, including an amount
of insulin delivered according to the basal rate pattern. The BG
management device determines at least one of an amount of insulin
over-delivered and an amount of insulin under-delivered during the
basal rate test using the insulin delivery information and the
sampled blood glucose data.
[0073] In some embodiments, the method 800 includes receiving the
insulin delivery information into the BG management device through
a communication port. As part of the basal rate test, the BG
management device may communicate a recommended change to the basal
rate pattern to the separate device using the communication port.
This is useful if the separate device is an insulin pump. In some
embodiments, the method 800 includes receiving the insulin delivery
information into the BG management device by manually entering the
insulin delivery information. The information is manually entered
via a user interface on the BG management device. Any recommended
changes to the basal rate pattern may be displayed on the BG
management device.
[0074] According to some embodiments, the BG management device does
not include a GM or an insulin pump. The basal insulin is delivered
according to a basal rate pattern using a second separate device,
such as an insulin pump for example. The method 800 includes
providing insulin delivery information, such as an amount of
insulin delivered according to the basal rate pattern, to the BG
management device using the second device.
[0075] The BG management device receives sampled blood glucose data
from the second separate device or a third device. At least one of
the insulin delivery information and the sampled blood glucose data
includes a time-stamp to allow for alignment of the insulin
delivery information and the blood glucose data. For example, the
time-stamp for the insulin delivery may be the time at which the
basal rate changes. The BG management device determines at least
one of an amount of insulin over-delivered and an amount of insulin
under-delivered during the basal rate test using the insulin
delivery information and the sampled blood glucose data. Any
recommended changes to the basal rate pattern may be displayed on
the BG management device.
[0076] In some embodiments, the method 800 includes executing the
basal insulin rate test during a substantially same time on
multiple days. In some examples, the method 800 includes executing
an overnight basal rate test. In some examples, the method includes
executing an overnight basal rate test that includes an overnight
basal rate calibration and verification technique.
[0077] FIG. 9 is a flow diagram of another method 900 of using a BG
management device to execute a basal rate test. At block 905,
sampled blood glucose data is received in a BG management device.
The blood glucose data may be obtained from a patient during a
specified time duration according to a specified basal insulin rate
pattern that is part of the basal rate test. At block 910, a time
varying correction factor c(t) is determined using the sampled
blood glucose data and the specified basal insulin rate pattern. At
block 915, a time varying basal rate pattern b(t) is determined.
The time varying basal rate pattern is to achieve the target blood
glucose baseline. The target blood glucose baseline may be a
constant or a time varying function g(t). In some embodiments, the
method 900 includes generating a change to the test-specified basal
rate pattern using the determined time varying basal rate pattern
b(t). In some embodiments, the method includes recommending a
change to the test-specified basal rate pattern, such as by using a
display for example.
[0078] The accompanying drawings that form a part hereof, show by
way of illustration, and not of limitation, specific embodiments in
which the subject matter may be practiced. The embodiments
illustrated are described in sufficient detail to enable those
skilled in the art to practice the teachings disclosed herein.
Other embodiments may be utilized and derived therefrom, such that
structural and logical substitutions and changes may be made
without departing from the scope of this disclosure. This Detailed
Description, therefore, is not to be taken in a limiting sense, and
the scope of various embodiments is defined only by the appended
claims, along with the full range of equivalents to which such
claims are entitled.
[0079] Such embodiments of the inventive subject matter may be
referred to herein, individually and/or collectively, by the term
"invention" merely for convenience and without intending to
voluntarily limit the scope of this application to any single
invention or inventive concept if more than one is in fact
disclosed. Thus, although specific embodiments have been
illustrated and described herein, it should be appreciated that any
arrangement calculated to achieve the same purpose may be
substituted for the specific embodiments shown. This disclosure is
intended to cover any and all adaptations, or variations, or
combinations of various embodiments. Combinations of the above
embodiments, and other embodiments not specifically described
herein, will be apparent to those of skill in the art upon
reviewing the above description.
[0080] The Abstract of the Disclosure is provided to comply with 37
C.F.R. .sctn.1.72(b), requiring an abstract that will allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in a single embodiment for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting an intention that the
claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single
disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own.
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