Figure 4.

Control-to-range vs open-loop glycemic regulation under nominal meals and perturbed insulin sensitivity. Closed-loop control starts at 13:00. Insulin sensitivity is 25% higher than nominal; consequently the open loop fails to prevent hypoglycemia. RCM and SSM act to maintain glycemic regulation within the range. On three occasions, risks for hypoglycemia are detected and the SSM further enforces attenuation of insulin delivery (red line, bottom). Between 20:00 and 22:30 insulin delivery is decreased compared to the nominal open-loop basal one. This explains the glucose peak around midnight and, as a consequence, the higher glucose profile during all night leading to the 125-mg/dl fasting glucose, even if nocturnal closed-loop insulin delivery does not differ from the open-loop basal.