Hypoglycemia prevention in closed-loop glycemic control via constraints in the glucose slope.

NICOLÁS ROSALES; LEÓN-VARGAS, FABIAN; HERNÁN DE BATTISTA; FABRICIO GARELLI

Viena

Conferencia; 11th International Conference on Advanced Technologies & Treatments for Diabetes; 2018

Kenes

Background and AimsWithin the development of closed-loop glucose controllers one of the major risks is the insulin induced hypoglycemia that can be produced due to controller overreaction. Here a supervisory methodology is proposed for the prevention of hypoglycemia, which differs from previous work (Revert et al., IEEE TBME 2013) by considering a limitation on the controlled variable or output of the system.MethodThe GSAFE (Glucose-based Safety Auxiliary Feedback Element) is a security layer based on the Sliding Mode Reference Conditioning technique. By means of a reduced-order glucose estimator, the GSAFE modifies the reference of the main controller to regulate the slope with which the glucose decreases, thereby limiting the insulin delivered by the controller as it can be seen in the illustrative figure below. The proposed technique can be applied to any control algorithm, both PID and MPC. ResultsThe algorithm was tested in a platform based on the UVa/Padova T1D Simulator (3-meals scenario with varying insulin sensitivity) with the controller given in Palerm CMPB 2011. Preliminary results show that the amount of hypoglycemic events and time spent in hypoglycemia were considerably reduced when applying the GSAFE, even for aggressive controller configurations. In particular, low glucose values were avoided in the late postpandrial period.ConclusionThe promising in-silico results obtained with the novel GSAFE methodology allow considering it as a potential safety layer for hypoglycemia prevention in the next clinical trials in Argentina, after the first and successful trial carried out in June 2017 without carbohydrates counting.