GLYCEMIC CONTROL AND DEVELOPMENT OF RETINOPATHY IN YOUTH-ONSET INSULIN-DEPENDENT DIABETES-MELLITUS - RESULTS OF A 12-YEAR LONGITUDINAL-STUDY

Background. In 1979, the authors began a prospective study of the natu ral history of retinopathy in youth-onset insulin-dependent diabetes m ellitus (IDDM). Their major goal was to determine if there was an asso ciation between glycemic control and the development and progression o f retinopathy. Methods: The study consisted of 420 individuals with ID DM (onset younger than 20 years of age) and no retinopathy at baseline . Study subjects were enrolled between 1979 and 1988. Stereo color fun dus photographs were obtained annually. Two eye endpoints were recorde d: duration when retinopathy was first detected, and when proliferativ e retinopathy was detected. Glycemic control was assessed by quarterly determinations of glycohemoglobin (GHb). Life-table analyses were per formed relating duration of diabetes, sex, GHb, and age of diabetes on set to development of retinopathy. Results: Retinopathy did not develo p before 2 years' duration or before puberty. The prevalence of retino pathy was 50% by 9 years' duration and 100% by 20 years' duration. Ret inopathy developed in females approximately 2 years sooner than in mal es, but plotting duration as postpubertal years resulted in nearly ide ntical rates. Retinopathy developed significantly earlier in subjects with prepubertal onset of diabetes than in subjects with postpubertal onset if duration was plotted as postpubertal years. When separated in to three groups based on GHb levels (<7.5%, 7.5%-9%, >9%), retinopathy developed approximately 2 years later in subjects in the less than 7. 5% GHb group than those in the higher GHb groups. Proliferative retino pathy developed in 11 subjects. Their mean GHb level was higher than t he mean GHb for those without proliferative retinopathy (10.9 versus 8 .6%; P < 0.01). The higher the level of GHb, the sooner proliferative changes were detected. Conclusion: Long-term glycemic control is signi ficantly related to both development and progression of retinopathy. P repubertal duration of diabetes is a significant risk factor for the d evelopment of retinopathy.