Enhanced IMC for Glucose Control in Type I Diabetics Using a Detailed Physiological Model

Administering ‘optimal’ amount of insulin to maintain the blood glucose concentration in the normoglycemic range is vital in Type 1 diabetics. In this study, internal model control (IMC) and enhanced IMC (EIMC) are developed for a diabetic due to their simple structure, better disturbance attenuation and uncertainty reduction. The step response of a detailed, first principles physiological model of the nominal diabetic patient is approximated by the first order plus time delay (FOPTD) model, which is then used for developing the IMC and EIMC. The two controllers are assessed based on their ability to track normoglycemic set point of 81.1 mg dl−1 while rejecting meal disturbance(s) both in the nominal patient case and about 580 perturbed patient cases, obtained by considering ±40% parametric variations in the patient model and all simulated using the first principles model. The results show that the EIMC is better than the IMC, and that the former can maintain the blood glucose above the dangerous hypoglycemic range in more than 90% of patient models studied.