The association of retinal changes with exercise microalbuminuria and with changes in systolic and diastolic blood pressure (BP) were evaluated in 162 young subjects with insulin-dependent (type 1) diabetes mellitus. Higher systolic and diastolic BPs at rest or after 10 or 20 min of exercise were significantly associated with more severe retinal changes in the subjects with diabetes compared to controls (P less than 0.02; global ANOVA). The mean (+/- SEM) exercise albumin excretion rate (AER) was 17.6 +/- 3.1 if there was no evidence of retinopathy compared to 81.5 +/- 23.5 when only microaneurysms were detected and 467.1 +/- 133.3 when more severe retinopathy was present. The percentage of subjects with abnormal AERs for these three retinal groups was 13, 30 and 60, respectively. (P less than 0.0001, chi-square test). It is clear that retinal changes relate to early renal changes, as monitored by exercise AERs and changes in resting and exercise BPs. It is concluded that the renal and retinal microvascular changes occur concurrently in young subjects with type 1 diabetes.