Type 1 diabetes mellitus (T1DM) is a metabolic disease in which the insulin-producing cells in the pancreas are destroyed by the immune system, affecting up to 3 million Americans and increasing yearly. T1DM is manageable with exogenous insulin therapy but is extremely burdensome and can lead to long term complications and shorter life spans. The Artificial Pancreas (AP) is currently being designed to automatically control blood glucose for people with T1DM. The AP is designed as a multi-component system including several devices, communication systems, and algorithms. The safety of the system is extremely important, because insulin can be extremely harmful or lethal at high doses. As a process engineering design, the full AP must have several layers of protection to reduce the likelihood of severe adverse events. The Health Monitoring System (HMS) has been designed as a multi-module safety system for the AP.

One of the most probable high-risk hazard of closed-loop insulin therapy is severe hypoglycemia, or low blood glucose, with symptoms such as nausea, dizziness, and coma or death of severe and prolonged. The Low Glucose Predictor (LGP), the first module of the HMS, was designed as an operator intervention safety layer to alert and treat for hypoglycemia. The LGP was integrated into the closed-loop AP system and tested in a 24 h feasibility study of twelve clinical subjects. There was an average of four alarms with rescue carbohydrates given per subject. The system successfully avoided hypoglycemia with no reference glucose values below the low hypoglycemia threshold of 60 mg/dL and no adverse events with symptoms. The Glucose Rate Increase Detector (GRID), used as a form of inferential control for hyperglycemia, was designed as the second module of the HMS.

The GRID was tuned using clinical trial data with unannounced meals and tested in simulation with closed-loop control with large, unannounced meals. With the GRID, the amount of time spent in hyperglycemia was significantly reduced when compared to closed-loop control with unannounced meals. With both HMS added to the AP, control was tighter with less adverse events, effectively increasing the safety of the system while improving control.