Real-time Adaptation to Changes in Insulin Sensitivity

The purpose of this research study is to test an automated blood glucose control system that includes a new component designed to adapt to stress. The importance of this component is that when Type 1 Diabetics are stressed (for example, from illness or infection), their body is resistant to the effects of insulin. The investigators will be adjusting their blood glucose using insulin and glucagon and making their body less sensitive to insulin with a steroid, hydrocortisone. Insulin is a hormone that lowers blood glucose. Glucagon raises blood glucose when it is low. Both are natural hormones made by people without diabetes. Hydrocortisone is a steroid that will increase their blood glucose temporarily and will be given every 4 hours. All subjects will participate in two 33 hour experiments. One experiment will use the adaptive version of the sensor-based glucose control system. The other study will use the original version of the control system, without the adaptive component, for the first 13 hours. Then, the adaptive component will be added to the glucose control system for the remaining 20 hours of the study. Our primary goal is to assess the effectiveness of the adaptive component to control glucose levels in the presence of steroid-induced insulin resistance in persons with Type 1 Diabetes Mellitus.