Figure 3.

Control-to-range vs open-loop glycemic regulation under perturbed meals. Closed-loop control starts at 13:00. Actual meals (blue dots) differ from nominal ones so that the open-loop therapy is no more optimal. Then, the RCM applies corrections in order to achieve a faster recovery of glycemic regulation within the range. The first two meals are greater than nominal, leading to administration of additional insulin. Because the control to range relies on nominal open-loop therapy, after the first two meals the initial rise of glycemia is similar to that observed in open loop. However, the RCM reacts and gives supplementary insulin so that recovery of within-range glycemia is faster than in open loop. This faster recovery is less evident after the first meal because closed-loop regulation is initiated at 13:00, when the glycemic peak has already been reached. The second meal is entirely under closed-loop regulation, and recovery within the range is therefore faster. The third meal is smaller than the nominal one and is delayed by 30 minutes. To cope with this perturbation, the RCM decreases the insulin basal value temporarily. On two occasions, a risk for hypoglycemia is detected and the SSM enforces attenuation of insulin delivery (red line, bottom).