Diabetes
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We investigated familial clustering of diabetic retinopathy and nephropathy in the families of 372 subjects from the Diabetes Control and Complications Trial (DCCT). These subjects had 467 first-degree relatives with IDDM or NIDDM. Family sizes ranged from two to six. ⋯ None of these correlations is statistically significant. The lack of significant correlation for the severity of nephropathy may reflect the relatively short duration of diabetes in the offspring of these families and the known high intrasubject variability of AERs. These data provide the first available evidence that the severity of diabetic retinopathy is influenced by familial (possibly genetic) factors and confirmatory evidence that such factors influence the development