The Efficacy of a Bi-hormonal Closed-loop System at Preventing Hypoglycemia during and after Exercise
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Type 1 diabetes mellitus (DM1) has had a growing incidence over the past decade. This autoimmune disease is characterized by the destruction of beta cells in the pancreas, which makes the individual unable to produce insulin, a hormone required for glucose use in the cells. DM1 patients must check their blood glucose levels many times throughout the day, and administer a carefully calculated amount of synthetic insulin to cover food and maintain a target range of blood glucose levels. The closed-loop system is a compilation of DM1 control devices that calculates the correct amount of insulin (and in the case of a bi-hormonal system, glucagon) needed to maintain a target range of blood glucose readings. This thesis seeks to determine whether it is necessary for an exercise announcement option to be programmed into the algorithm so that the system can prevent hypoglycemia during and after exercise. It was found that using the closed loop with an exercise announcement is no more efficient at preventing hypoglycemia during and after exercise than a closed loop system without an exercise announcement or an open loop system (p=0.57 and 0.55, respectively). However, it is important to note that these results are only preliminary results of the Artificial Pancreas Control (APC) study in progress at Oregon Health and Sciences University; this thesis will present results from the first seven subjects of the APC study. Hardware errors, failed infusion sites, and early termination of individual subject studies make for a small sample size, and thus insignificant results. However, closed loop technology is promising, and once the APC study is completed it will act as a guide for future research in the field. Artificial pancreas technology is ever moving forward, and will eventually create a device or system that allows type 1 diabetics to live without constantly thinking of diabetes care and blood glucose control.