103 Indians (74 females, 29 males) with NIDDM diagnosed before age 30 yr on the basis of the revised WHO diagnostic criteria were studied in order to assess the prevalence of microvascular complications. The mean duration of NIDDM in the subjects was 11 yr (range 2-38 yr). 24 patients (23%) eventually required insulin therapy for control after a mean interval of 11.8 yr (range 5-38 yr). Diabetic retinopathy was present in 37 patients (35.9%), of whom 6 had proliferative retinopathy. Nephropathy was found in 16 patients (15.5%). The mean GFR of these patients was 46.8 ml/min, compared to a mean of 97.1 ml/min in 12 of the patients without nephropathy who had a similar mean duration of disease. The mean duration of disease in patients with retinopathy and nephropathy was 14.9 yr and 14.8 yr respectively. In the patients who eventually required insulin therapy both retinopathy (75%) and nephropathy (41%) were more common but the mean duration of disease in these patients was longer (16 yr vs 9 yr). This study has underlined the heterogeneity of NIDDM in the young, as microvascular complications are by no means uncommon in South African Indians with the disease.