A Comparative Study of Different Types of Controllers Used for Blood Glucose Regulation System Surekha Kamath, 1 * V. I. George 1 and Sudha Vidyasagar 2 1. Department of ICE MIT Manipal, Karnataka, India 2. Department of Medicine K.M.C. Manipal, Karnataka, India Maintaining the glucose concentration in normoglycemic range in Type I diabetic patients is challenging. In this study H ∞ control is applied for the insulin delivery to prevent the hyperglycaemic levels in a type I diabetic patient. A nonlinear model is linearized around nominal condition and reduced for control synthesis. H ∞ controller was compared with the two other types of controller and performance results shows evaluatory results. Le maintien de la concentration en glucose dans la plage normoglyc´ emique chez les patients souffrant d’un diab` ete de type I repr´ esente tout un d´ efi. Dans cette ´ etude, un contrˆ oleur H∞ est appliqu´ e pour l’administration de l’insuline afin d’´ eviter les niveaux d’hyperglyc´ emie chez ces patients. Un mod` ele non lin´ eaire est lin´ earis´ e autour d’une condition nominale et r´ eduit pour une synth` ese de contrˆ ole. Le contrˆ oleur H∞ a fait l’objet d’une comparaison avec deux autres types de contrˆ oleur et les r´ esultats de performance montrent des r´ esultats d’´ evaluation. Keywords: PID control, robust control, glucose-insulin modelling INTRODUCTION T he diabetes mellitus is a group of metabolic diseases characterised by a high blood glucose concentration (hyper- glycemia) resulting from defects in insulin secretion, insulin action, or both phenomena. This complication has largely exceeded its growth expectative, and its impact in the worldwide health-care problem has raised the interest of the scientific com- munity to provide control algorithms that can be implemented for the real-time patient treatment given in Carson and Deutsch (1992). In a type 1 diabetes mellitus (TIDM) patient, the pan- creas is not able of producing the insulin at all. This problem can produce short- and long-term illnesses (diabetes coma, nephropa- thy, retinopathy, and other tissue damage) due to the variations in the blood glucose level (BGL). As a result, the BGL has to be monitored externally to maintain it regulated by applying insulin infusions in a regular scheme. Meanwhile, in a healthy patient, the insulin released by the pancreas maintains the basal blood glucose concentration around euglycemic (normoglycemic) levels 70–120mg/dl. Hence, the pancreas provides a basal rate of 22 mU/min Guyton et al. (1978) and Bode (2004) and it increases this amount during meal intakes (postprandial peak), in order to process the glucose absorbed from the gut. Consequently, in the absence of insulin, the blood glucose level for a TIDM patient can decrease or increase above euglycemic levels (hypoglycemia and hyperglycemia, respectively) for long periods of time. In fact, the TIDM patient requires external insulin for survival. However, the Diabetes Control and Complications Trial (DCCT, 1993) showed that an intensive insulin therapy can reduce the incidence of long-term illnesses. Therefore, an inten- sive therapy is encouraged for TIDM patients prescribed either by a continuous-infusion pump (CIP), or a multiple daily injection regimen (MDIR). With this consideration, if an intensive therapy is followed by the patient, the prescribed insulin treatment must be carefully studied by the physician, and it should be constantly updated according with the results achieved. A wearable artificial pancreas, consisting in a feedback control system regulating insulin delivery according to real time glycaemic changes, is not yet available because of many ∗ Author to whom correspondence may be addressed. E-mail address: surekakamath2k4@yahoo.com Can. J. Chem. Eng. 87:812–817, 2009 © 2009 Canadian Society for Chemical Engineering DOI 10.1002/cjce.20219 | 812 | THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING | | VOLUME 87, OCTOBER 2009 |