- People with type 1 diabetes rely on exogenous insulin infusions to maintain their blood glucose concentration at the target value of 81 mg and within the desired range of 60-120 mg. These infusions usually result in significant deviations from the target value and the desired range, primarily due to the open-loop nature of the controller. In this chapter model-based parametric controllers are derived to obtain optimal insulin delivery rate as an explicit function of the state of the patients. This is expected to greatly simplify the insulin delivery mechanism and improve the quality of life of the patients via a closed-loop glucose control system. Issues pertaining to uncertainty in the model parameters due to inter- and intrapatient variability are also addressed by deriving a feasible control law. Physician's performance criteria, which place more emphasis on reducing negative deviations from the target value than on positive deviations from the target value, are also incorporated by proposing two strategies within the parametric control framework. These developments are expected to increase the safety and convenience levels of the patients. 2007 Wiley-VCH Verlag GmbH & Co. KGaA.