Comparison of Algorithms for the Closed-Loop Control of Blood Glucose Using the Artificial Beta Cell

Over the past 15 years, several algorithms have been proposed and used for closed-loop blood glucose regulation. Their intent is to artificially replace the normal responses of the pancreatic beta cell absent in insulin-dependent diabetes. All of these algorithms calculate insulin infusion rates on the basis of minute-by-minute measurements of whole blood glucose concentration and its calculated rate of rise or fall. In addition, various techniques are employed to compensate for measurement delay time and the presence of noise in the measured signals. The goal of these feedback systems is to normalize blood glucose in diabetes mellitus. Interestingly, some recently "optimized" versions provide only a near normalization of glycemia in patients with insulin-dependent diabetes, a degree ofglycemic control which is not significantly different from intensified conventional insulin therapy.