A study was performed to determine the relationship between level of long-term antecedent diabetic control and early diabetic retinopathy changes. Fifty-eight insulin dependent diabetics aged 14 to 17 1/2 years, with duration of diabetes of at least 8 years, were studied. Glycosylated hemoglobins were assessed a mean of 8.5 times per patient, over a mean period of 3.1 years, representing 28% of the mean duration of diabetes in this patient population. Fluorescein angiography, obtained according to a standardized technique, was assessed in masked fashion for number of microaneurysms, presence of abnormal areas of capillary nonperfusion, and presence of intraretinal dye leakage. Sixty-four percent of the study population showed some evidence of retinopathy. There was a high correlation found between degree of metabolic control as measured by glycosylated hemoglobin level, and presence of early retinopathy changes as defined by angiography.