Data from the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) demonstrated that the incidence of diabetic complications is directly related to glycemic control. The results of the Diabetes Control and Complications Trial and Stockholm Study showed that intensive insulin therapy and improved glycemic control reduced diabetic complications in people with type 1 diabetes. Results of the U.K. Prospective Diabetes Study Group and the Kumamoto trial also support the relationship between glycemic control and diabetic complications in individuals with type 2 diabetes. Preliminary WESDR health outcomes data suggest that higher levels of glycemia are related to a decreasing quality of life. This study and others showing that higher levels of glycemia are associated with an increased incidence of complications suggest that it is the complications of diabetes that contribute to a decrease in quality of life. Despite evidence of the benefits of improved glycemic control, a large percentage of people with diabetes maintain poor glucose control in part because of the limitations of the therapies available for diabetes management.