PID and LQG controllers for diabetes system with internal delay: a comparison study

Abstract

Closed-loop treatment for insulin dependent type 1 diabetes patients is a recent medical practice in insulin delivery (bionic pancreas) which aims to achieve tight control of glucose level in plasma and ensure minimizing risk of hypoglicemia. Among those most popular closed-loop controller strategies, proportional integral derivative (PID) and linear quadratic Gaussian (LQG) controllers are designed and compared for insulin delivery in diabetic patients. The controllers are designed based on individual and nominal model which is to study the ability of each controller in order to maintain blood glucose concentration for similar patient’s dynamic. The comparison is conducted numerically not only for for patients suffering type 1 diabetes mellitus (T1DM), but also type 2 diabetes mellitus (T2DM), and double diabetes mellitus (DDM) in the present of internal delay systems, which causes instability. The responses show that the proposed PID controller is better at maintaining the blood glucose level in the normal range for a longer delay of delay in hepatic glucose production. The patient with longer performing physical exercise has lower oscillation peaks in blood glucose concentration.