Method and system for closed-loop control of an artificial pancreas
Methods and systems for controlling an insulin pump in response to glucose measurements are responsive to a base insulin delivery profile and a temporary insulin delivery profile. These can be used, e.g., to control blood glucose level of a subject using a continuous glucose monitor and an insulin infusion pump. During a selected time range, an insulin amount for the pump to supply is determined using the temporary insulin delivery profile. Outside that time range, the insulin amount is determined using the base insulin delivery profile. The temporary insulin delivery profile can specify an exact amount to be supplied (a “hard” profile), a nominal amount to be supplied if doing so does not drive glucose out of a desired zone (“soft”), or a soft profile with a minimum amount of insulin to be delivered (“semi-soft”).
1. Apparatus for the delivery of insulin, the apparatus comprising:
a) a glucose monitor adapted to measure respective glucose levels of a subject at discrete time intervals and provide respective glucose measurement data indicating each measured glucose level;
b) an insulin infusion pump configured to deliver insulin in response to a delivery control signal;
c) a memory configured to store a base insulin delivery profile;
d) an interface adapted to selectively receive a temporary insulin delivery profile extending over a selected time range of the time intervals and to provide a first signal indicating whether the temporary insulin delivery profile was received; and
e) a controller adapted to, for each of a plurality of the discrete time intervals:
i) receive the glucose measurement data for that time interval from the glucose monitor;
ii) determine an insulin delivery amount for that time interval using the received temporary insulin delivery profile when the time interval is in the selected time range and in response to the first signal and, when the time interval is outside the selected time range, using model predictive control based on a selected target glucose concentration range, the received glucose measurement data, and the stored base insulin delivery profile; and
iii) provide to the insulin infusion pump a delivery control signal corresponding to the determined insulin delivery amount, whereby a corresponding amount of insulin is delivered.
2. The apparatus according to claim 1 , wherein the interface is adapted to receive the temporary insulin delivery profile by receiving change information and modifying the stored base insulin delivery profile in the selected time range according to the change information to provide the temporary insulin delivery profile.
3. The apparatus according to claim 1 , wherein the controller is adapted to determine the insulin delivery amount for a selected time interval using:
a) if the temporary insulin delivery profile was not received or the selected time interval is outside the selected time range, the controller is adapted to use the selected target glucose concentration range, the received glucose measurement data, the stored base insulin delivery profile;
b) otherwise, the controller is adapted to use the selected target glucose concentration range, the received glucose measurement data, and the received temporary insulin delivery profile.
4. The apparatus according to claim 1 , wherein the controller is further adapted to, in response to the first signal and if a selected time interval is in the selected time range, constrain the determined insulin delivery amount for the selected time interval to be at least a difference between respective values of the temporary insulin delivery profile and the stored base insulin delivery profile for the selected time interval.
5. The apparatus according to claim 1 , wherein the controller is further adapted to:
a) predict an excursion of a glucose level of the subject from the selected target glucose range using a safety model and at least some of the glucose measurement data for a plurality of the time intervals; and
b) reduce the determined insulin delivery amount according to the predicted excursion.
6. The apparatus according to claim 1 , wherein the temporary insulin delivery profile defines a first subrange and a second subrange of the selected time range and wherein the temporary insulin delivery profile specifies a higher rate of insulin delivery in the first subrange and a lower rate of insulin delivery in the second subrange.
7. The apparatus according to claim 1 , wherein the glucose monitor includes a plurality of glucose sensors.
8. The apparatus according to claim 1 , wherein the interface is further adapted to provide an activation signal and the controller, in response to the activation signal, retrieves the stored base insulin delivery profile and retrieves or determines the insulin delivery amount.
9. Apparatus for the delivery of insulin, the apparatus comprising:
a) a glucose monitor adapted to measure respective glucose levels of a subject at discrete time intervals and provide respective glucose measurement data indicating each measured glucose level;
b) an insulin infusion pump configured to deliver insulin in response to a delivery control signal;
c) a memory configured to store a base insulin delivery profile;
d) an interface adapted to receive a temporary insulin delivery profile extending over a selected time range of the time intervals; and
a controller adapted to, for each of a plurality of the discrete time intervals:
i) receive the glucose measurement data for that time interval from the glucose monitor;
ii) when that time interval is in the selected time range, retrieve a corresponding insulin delivery amount from the temporary insulin delivery profile and when the time interval is outside the selected time range, determine an insulin delivery amount for that time interval using model predictive control based on a selected target glucose concentration range, the received glucose measurement data, and the base insulin delivery profile; and
iii) provide to the insulin infusion pump a delivery control signal corresponding to the insulin delivery amount, whereby a corresponding amount of insulin is delivered.
10. The apparatus according to claim 9 , wherein the controller is further adapted to:
a) predict an excursion of a glucose level of the subject from the selected target glucose range using a safety model and at least some of the glucose measurement data for a plurality of the time intervals; and
b) reduce the determined insulin delivery amount according to the predicted excursion.
11. The apparatus according to claim 9 , wherein the glucose monitor includes a plurality of glucose sensors.
12. The apparatus according to claim 9 , wherein the interface is further adapted to provide an activation signal and the controller, in response to the received activation signal, retrieves the stored base insulin delivery profile and retrieves or determines the insulin delivery amount.