Insulin injection therapy is widely practiced for the maintenance of blood glucose levels within the normoglycemic range (70-100 mg/dL) for type I diabetics. Several proportional-integral-derivative (PID) controllers are designed using classical and modern tuning techniques, for a diabetic to specify the insulin dosage on a continuous glucose measurement basis. The PID controllers are then assessed with a detailed physiological model of diabetic patients for their ability to reject meal disturbances and their robustness in the presence of parametric uncertainties. One of the recently developed PID tuning techniques is able to maintain the glucose concentration above the hypoglycemic range (<60 mg/dL) in 95% (and 100% with fine-tuning) of 577 diabetics tested, while rejecting both single- and multiple-meal disturbance(s).