Sensor model supervisor for a closed-loop insulin infusion system

Patent metadata

Field	Value
Publication number	US-2016256629-A1
Application number	US-201615138540-A
Country	US
Kind code	A1
Filing date	Apr 26, 2016
Priority date	Aug 30, 2012
Publication date	Sep 8, 2016
Grant date	—

Abstract

An insulin infusion device includes a processor architecture, and a memory element that stores executable instructions to perform a method of controlling delivery of insulin to a user. The method operates the device in a closed-loop mode to deliver insulin, obtains patient-specific parameters for a current time sample, and estimates a plasma insulin value and a blood glucose value for the user based on at least some of the patient-specific parameters. The estimating is also based on a previously estimated plasma insulin value obtained for a previous time sample, and a previously estimated blood glucose value obtained for the previous time sample. A predicted sensor glucose value is generated for the current time sample, and the closed-loop mode or a safe basal mode is selected for controlling operation of the insulin infusion device in accordance with the selected mode.

First claim

What is claimed is:

1 . An insulin infusion device comprising:
a reservoir for insulin to be delivered from the insulin infusion device to a body of a user; a processor architecture comprising at least one processor device; and at least one memory element associated with the processor architecture, the at least one memory element storing processor-executable instructions that, when executed by the processor architecture, perform a method of controlling delivery of insulin from the insulin reservoir to the body of the user, the method comprising:
automatically operating the insulin infusion device in a closed-loop mode to deliver insulin from the insulin reservoir to the body of the user;
obtaining, for a current time sample, a patient-specific insulin gain value (KI), a patient-specific fasting insulin basal rate value (IBasal), a patient-specific fasting blood glucose value (SGBase), a meter blood glucose value (MBG), and an insulin delivered value (Iin) that represents an amount of insulin delivered since a preceding time sample;
estimating, for the current time sample, an estimated plasma insulin value (Ip t ) and an estimated blood glucose value (G t ) for the user, the estimating based on at least some of the values of KI, IBasal, SGBase, MBG, and (Iin), and the estimating further based on a previously estimated plasma insulin value obtained for a previous time sample (Ip t-1 ), and a previously estimated blood glucose value obtained for the previous time sample (G t-1 );
generating, for the current time sample, a predicted sensor glucose value (SGp) for the user, the generating based on the values of G t and SGBase for the current time sample;
selecting either the closed-loop mode or a safe basal mode, based on at least some of the values of SGp, SG, Ip t , and G t for the current time sample; and
controlling operation of the insulin infusion device to deliver insulin to the body of the user in accordance with the selected mode.

2 . The insulin infusion device of claim 1 , wherein the selecting comprises:
selecting between the closed-loop mode, a first safe basal mode, or a second safe basal mode, the first safe basal mode representing a higher basal rate of insulin relative to the second safe basal mode.

3 . The insulin infusion device of claim 2 , wherein the method performed by the processor architecture further comprises:
calculating a difference (SGpThDiff) between the predicted sensor glucose value (SGp) and a low threshold value in accordance with the expression: SGpThDiff=SGp−Low Threshold, wherein the second safe basal mode is selected when SGpThDiff<0.

4 . The insulin infusion device of claim 1 , wherein the method performed by the processor architecture further comprises:
collecting, during a predetermined period of time, MBG values, sensor glucose (SG) values from a continuous glucose sensor, meal-related data, insulin history data, and total daily insulin data associated with the user; and calculating, for each predetermined period of time, the values of KI, IBasal, and SGBase, the calculating based on at least some of the collected MBG values, SG values, meal-related data, insulin history data, and total daily insulin data.

5 . The insulin infusion device of claim 4 , wherein the method performed by the processor architecture further comprises:
searching the SG values for a fasting glucose value for the user, wherein the values of IBasal and SGBase are calculated based on an identified fasting glucose value.

6 . The insulin infusion device of claim 1 , wherein:
IBasal represents an estimated basal rate needed to maintain the fasting blood glucose value (SGBase) for the user; and SGBase represents an estimated fasting blood glucose value for the user when insulin is delivered at the fasting insulin basal rate value (IBasal).

7 . The insulin infusion device of claim 1 , wherein the method performed by the processor architecture further comprises:
resetting the value of G t-1 with each new value of MBG in accordance with the expression: G t-1 =MBG−SGBase.

8 . The insulin infusion device of claim 1 , wherein the method performed by the processor architecture further comprises:
processing at least some of the values of SGp, SG, Ip t , and G t for the current time sample to detect a sensor under-reading condition, wherein the safe basal mode is selected only in response to detecting the sensor under-reading condition.

9 . An insulin infusion system comprising:
a continuous glucose sensor that generates sensor data indicative of sensor glucose values (SG) for a user; and an insulin infusion device coupled to receive the sensor data generated by the continuous glucose sensor, the insulin infusion device comprising an insulin reservoir for insulin to be delivered from the insulin infusion device to the user, a processor architecture comprising at least one processor device and further comprising at least one memory element associated with the processor architecture, the at least one memory element storing processor-executable instructions that, when executed by the processor architecture, cause the insulin infusion device to perform a method comprising: automatically operating the insulin infusion device in a closed-loop mode to deliver insulin from the insulin reservoir to the body of the user; obtaining, for a current time sample, a patient-specific insulin gain value (KI), a patient-specific fasting insulin basal rate value (IBasal), a patient-specific fasting blood glucose value (SGBase), a meter blood glucose value (MBG), and an insulin delivered value (Iin) that represents an amount of insulin delivered since a preceding time sample; estimating, for the current time sample, an estimated plasma insulin value (Ip t ) and an estimated blood glucose value (G t ) for the user, the estimating based on at least some of the values of KI, IBasal, SGBase, MBG, and (Iin), and the estimating further based on a previously estimated plasma insulin value obtained for a previous time sample (Ip t-1 ), and a previously estimated blood glucose value obtained for the previous time sample (G t-1 ); generating, for the current time sample, a predicted sensor glucose value (SGp) for the user, the generating based on the values of G t and SGBase for the current time sample; selecting either the closed-loop mode or a safe basal mode, based on at least some of the values of SGp, SG, Ip t , and G t for the current time sample; and controlling operation of the insulin infusion device to deliver insulin to the body of the user in accordance with the selected mode.

10 . The system of claim 9 , wherein the selecting comprises:
selecting between the closed-loop mode, a safe nominal basal mode, or a safe low basal mode, the safe nominal basal mode representing a higher basal rate of insulin relative to the safe low basal mode.

11 . The system of claim 9 , wherein the method performed by the processor architecture further comprises:
collecting, during a predetermined period of time, MBG values, sensor glucose (SG) values from a continuous glucose sensor, meal-related data, insulin history data, and total daily insulin data associated with the user; and calculating, for each predetermined period of time, the values of KI, IBasal, and SGBase, the calculating based on at least some of the collected MBG values, SG values, meal-related data, insulin history data, and total daily insulin data.

12 . The system of claim 9 , wherein:
IBasal represents an estimated basal rate needed to maintain the fasting blood glucose value (SGBase) for the user; and SGBase represents an estimated fasting blood glucose value for the user when insul

Assignees

• Medtronic Minimed Inc

Inventors

• Grosman Benyamin
• Wu Di
• Roy Anirban
• Parikh Neha J

Classifications

• G06F19/3468

  Physics · mapped topic

• A61M2230/201

  Glucose concentration · CPC title

• A61M5/14244

  adapted to be carried by the patient, e.g. portable on the body · CPC title

• A61M5/1723 Primary

  using feedback of body parameters, e.g. blood-sugar, pressure (measurement of body parameters A61B5/00) · CPC title

• A61M2205/52

  with memories providing a history of measured variating parameters of apparatus or patient · CPC title