Sensor model supervisor for a closed-loop insulin infusion system

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 (Ipt) and an estimated blood glucose value (Gt) 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 (Ipt-1), and a previously estimated blood glucose value obtained for the previous time sample (Gt-1);
• generating, for the current time sample, a predicted sensor glucose value (SGp) for the user, the generating based on the values of Gt 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, Ipt, and Gt 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.

A method of operating an insulin infusion device to regulate delivery of insulin to a body of a user, the method comprising:

• obtaining, from a continuous glucose sensor, sensor glucose (SG) values for the user;
• calculating, from the obtained SG values, a patient-specific fasting insulin basal rate value (IBasal) and a patient-specific fasting blood glucose value (SGBase), wherein IBasal represents an estimated basal rate needed to maintain SGBase for the user, and wherein SGBase represents an estimated fasting blood glucose value for the user when insulin is delivered at IBasal;
• using the values of IBasal and SGBase to calculate, for a current time sample, an estimated plasma insulin value (Ipt) and an estimated blood glucose value (Gt) for the user;
• and
• using the values of Ipt, Gt, SGBase, and SG to select either a closed-loop mode of operation, a safe nominal basal mode of operation, or a safe low basal mode of operation for the insulin infusion device;
• and
• controlling delivery of insulin from the insulin infusion device to the body of the user, in accordance with the selected mode of operation.