System diagram of the " Automatic Insulin Infusion System" (AIIS) for Inpatient Treatment. System diagram of the "Automatic Insulin Infusion System" (AIIS) for Inpatient Treatment(see text). Glucose concentration measured by the subcutaneous sensor is compared to the reference glycemia (100 mg/dL). The result becomes the input for the controller. If the result is either normoglycemia (90-120 mg/dL) or hyperglycemia (> 120 mg/dL), or if the glycemia is rising too fast, then the controller signals the insulin pump, that releases insulin solution at a particular rate (international units per hour). On the other hand, if the input to the controller reflects a hypoglycemia (i.e., glycemia < 60 mg/dL), or if the glycemia, albeit being within normal range, is falling too fast, then the controller signals the glucose pump. Every five minutes, the subcutaneous glucose sensor submits the results of a new glucose estimate to the input of the controller, and the whole process is repeated.