Optimal management of the diabetic patient includes normalization of plasma glucose concentration. Attainment of this goal is difficult because both food and stress result in acute elevations of blood glucose that cannot be matched with a single subcutaneous injection of NPH insulin. This paper examines the currently available methods for delivery of insulin to the diabetic subject and the degree of metabolic control attained. It suggests that optimal diabetic control will be achieved only when newer methods of insulin delivery are available to the clinician that match plasma insulin requirements to the simultaneous plasma glucose concentration.