Relation of glycemic control to diabetic microvascular complications in diabetes mellitus

Objective: To describe the relation between glycated hemoglobin and the incidence or progression, or both, of diabetic microvascular complications in persons with insulin-dependent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM). Design: Population-based cohort study. Setting: An 11-county area in southern Wisconsin. Patients: All persons with IDDM diagnosed before age 30 and taking insulin (n = 996) and a probability sample (based on duration of disease) of persons diagnosed with diabetes at age 30 or older who were either taking insulin (n = 674) or not taking insulin (n = 696) and who participated in a baseline examination from 1980 to 1982. Survivors of the cohort were re-examined again in 1984 to 1986 and 1990 to 1992. Measurements: The incidence and progression of diabetic retinopathy was determined by masked grading of stereoscopic color fundus photographs using the modified Early Treatment Diabetic Retinopathy Study severity scale. Gross proteinuria was determined using a dipstick. Ten-year incidence of renal dialysis or transplantation or loss of tactile sensation or of temperature sensitivity was based on self-reported history. Results: The glycated hemoglobin level at baseline was strongly related to the incidence or progression, or both, of diabetic retinopathy, the incidence of gross proteinuria, and the incidence of loss of tactile sensation or temperature sensitivity in persons with either IDDM or NIDDM. Conclusions: These prospective epidemiologic data suggest that glycemic control is similarly related to the incidence and progression of diabetic microvascular complications in both IDDM and NIDDM. However, further evidence from clinical trials in persons with NIDDM is necessary to assess the risks and benefits of such treatment in preventing these complications.