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 operating in conjunction with a glucose sensor and 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 controller contained within the housing, wherein the controller monitors the operation of the infusion pump and glucose sensor by storing historical meal information for meals consumed by the user, said meal information including a carbohydrate content and a meal-type indicator for each said meal, storing historical insulin-delivery information including, for each instance of insulin delivery, an insulin amount and a delivery pattern, generating a predicted glucose concentration profile based on the historical meal and insulin-delivery information, generating a sensor glucose concentration profile based on periodic measurements obtained from the glucose sensor, and determining whether, for a given point in time, the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than a pre-determined error value.   
     
     
         2 . The infusion pump of  claim 1 , wherein the controller provides a warning to the user when the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than the pre-determined error value. 
     
     
         3 . The infusion pump of  claim 1 , wherein the controller periodically repeats the determining step and provides a warning to the user when the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than the pre-determined error value for a plurality of successive determinations. 
     
     
         4 . The infusion pump of  claim 1 , wherein, for each meal, the meal-type indicator is the amount of time corresponding to the peak of the meal's appearance rate. 
     
     
         5 . A method of monitoring the operation of a diabetes-management system having a glucose sensor, a controller, and an insulin delivery pump, the method comprising:
 (a) storing historical meal information for meals consumed by a user, said meal information including a carbohydrate content and a meal-type indicator for each said meal;   (b) storing historical insulin-delivery information including, for each instance of insulin delivery, an insulin amount and a delivery pattern;   (c) generating a predicted glucose concentration profile by the controller based on the historical meal and insulin-delivery information;   (d) generating a sensor glucose concentration profile based on periodic measurements obtained from the glucose sensor; and   (e) determining whether, for a given point in time, the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than a pre-determined error value.   
     
     
         6 . The method of  claim 5 , further including providing a warning to the user when the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than the pre-determined error value. 
     
     
         7 . The method of  claim 6 , wherein the warning is a member selected from the group consisting of an alarm, a visual signal, a vibrating indicator, and combinations thereof. 
     
     
         8 . The method of  claim 5 , further including displaying the predicted and sensor glucose concentration profiles for the user. 
     
     
         9 . The method of  claim 8 , wherein the profiles are displayed on the insulin delivery pump. 
     
     
         10 . The method of  claim 5 , wherein, for each meal, the meal-type indicator is the amount of time corresponding to the peak of the meal's appearance rate. 
     
     
         11 . The method of  claim 5 , wherein the determination of step (e) is repeated periodically, and the method further includes providing a warning to the user when the difference between the sensor glucose concentration value and the predicted glucose concentration value is larger than the pre-determined error value for a plurality of successive determinations. 
     
     
         12 . The method of  claim 5 , wherein said delivery pattern is either a single-bolus pattern or an extended-bolus pattern. 
     
     
         13 . The method of  claim 5 , wherein the periodic measurements obtained from the glucose sensor are transmitted directly to the controller. 
     
     
         14 . The method of  claim 5 , wherein the diabetes-management system is a closed-loop system.