Model predictive method and system for controlling and supervising insulin infusion

Abstract

A system and method for controlling and monitoring a diabetes-management system through the use of a model that predicts or estimates future dynamic states of glucose and insulin from variables such as insulin delivery or exogenous glucose appearance as well as inherent physiological parameters. The model predictive estimator can be used as an insulin bolus advisor to give an apriori estimate of postprandial glucose for a given insulin delivery profile administered with a known meal to optimize insulin delivery; as a supervisor to monitor the operation of the diabetes-management system; and as a model predictive controller to optimize the automated delivery of insulin into a user's body to achieve a desired blood glucose profile or concentration. Open loop, closed-loop, and semi-closed loop embodiments of the invention utilize a mathematical metabolic model that includes a Minimal Model, a Pump Delivery to Plasma Insulin Model, and a Meal Appearance Rate Model.

1 . An infusion pump for infusing insulin from a reservoir into a body of a user, the infusion pump comprising:
 a housing;   a drive mechanism contained within the housing and operatively coupled to the reservoir to deliver insulin from the reservoir through a fluid path into the body of the user; and   a model predictive controller contained within the housing, wherein the controller optimizes the delivery of insulin into the user's body so as to achieve a desired blood glucose concentration by measuring the user's current blood glucose concentration, generating a pre-defined desired glucose concentration profile based on the current blood glucose concentration, generating an insulin-delivery profile to achieve said desired concentration over a predetermined time period, generating a predicted glucose concentration profile for said time period based on the current glucose concentration and the generated insulin-delivery profile, calculating a difference between the generated glucose concentration profile and the pre-defined glucose concentration profile, iteratively identifying an optimal insulin-delivery profile as the profile that minimizes said difference, and generating commands for the drive mechanism to deliver insulin to the user according to the optimal insulin-delivery profile for a pre-set period of time defining a time step.   
     
     
         2 . The infusion pump of  claim 1 , wherein the controller re-optimizes the delivery of insulin into the user's body every time step for the duration of the predetermined time period. 
     
     
         3 . The infusion pump of  claim 1 , wherein the pre-defined glucose concentration profile is defined per American Diabetes Association (ADA) guidelines. 
     
     
         4 . The infusion pump of  claim 1 , wherein said predetermined time period is at least one hour long, and each said time step is at most five minutes long. 
     
     
         5 . A method for optimizing the delivery of insulin into a body of a user so as to achieve a desired blood glucose concentration, the method comprising:
 (a) measuring the user's current blood glucose concentration;   (b) generating a pre-defined desired glucose concentration profile based on the current blood glucose concentration;   (c) generating an insulin-delivery profile to achieve said desired concentration over a predetermined time period;   (d) generating a predicted glucose concentration profile for said time period by a model predictive controller using the current glucose concentration and the generated insulin-delivery profile as inputs;   (e) calculating a difference between the generated glucose concentration profile and the pre-defined glucose concentration profile;   (f) iteratively repeating steps (a)-(e) and identifying an optimal insulin-delivery profile as the delivery profile that produces the minimal difference calculated in step (e);   (g) delivering insulin to the user according to the optimal insulin-delivery profile for a pre-set period of time defining a time step; and   (h) for the duration of the predetermined time period, repeating steps (a)-(g) every time step.   
     
     
         6 . The method of  claim 5 , wherein the pre-defined glucose concentration profile is defined per American Diabetes Association (ADA) guidelines. 
     
     
         7 . The method of  claim 5 , wherein said predetermined time period is at least one hour long, and each said time step is at most five minutes long. 
     
     
         8 . The method of  claim 5 , wherein the controller is in communication with an insulin delivery system in a closed loop and, at each time step, generates commands that instruct the insulin delivery system to infuse insulin into the body of the user according to the optimal insulin-delivery profile.