Automatic Blood Glucose Control in Diabetes

Abstract

In this thesis, a closed-loop control algorithm for regulating the blood glucose concentration in type 1 diabetic patients is developed. Two control criteria are imposed on the system, namely: -Avoidance of hypoglycemia. (blood glucose concentrations should always be above $3 frac{mmol}{L}$) -Reduction in the average blood glucose concentration compared to what is achieved with manual control. (average blood glucose concentrations should preferably be less than $7.0 frac{mmol}{L}$). The developed control algorithm manages to fulfill both these control criteria. Hypoglycemia is avoided, and average blood glucose concentrations is reduced by $20%$ and $22%$ to a level of $7.0 frac{mmol}{L}$ and $6.9 frac{mmol}{L}$ in the two test subjects. However, further experiments should be carried out to test the robustness of the control algorithm, and a thorough investigation of safety issues for the user needs to performed. As a basis for the implementation of closed-loop blood glucose control, data from three diabetic patients is used to identify the parameters of a proposed mathematical model of the human insulin-glucose regulatory system. The identification process reveals that there is large variations between individual patient's parameter values, and the difference in insulin sensitivity is found to be specially high, both between and within patients.