The study was done to assess whether there was a familial aggregation of diabetic kidney disease (DKD) in Type 2 diabetic subjects. The profile of associated complications was also studied. Two groups of diabetic siblings of Type 2 diabetic patients, matched for age, body mass index (BMI) and duration of diabetes mellitus were studied. The siblings also had Type 2 diabetes. Group A comprised of siblings of probands with diabetic nephropathy and retinopathy (n = 30, M:F = 20:10) and Group B were siblings of probands without diabetic nephropathy or microalbuminuria (MAU) (n = 30, M:F = 14:16). Anthropometry, measurement of blood pressure and tests for proteinuria, MAU and retinopathy and ECG and biothesiometry were carried out for all study subjects. Persistent proteinuria was present in 15 (50%) siblings in group A and none in group B. MAU was detected in 26.7% (n = 7) in Group A and 3.3% (n = 1) in Group B (P = 0.057). Thus a total of 22 out of 30 cases in Group A had albuminuria. In Group A, seven (23.3%) had proteinuria and hypertension. Hypertension was present in nine (30.0%) in group A, and in five (16.7%) in group B (NS). Occurrence of retinopathy was found to be significantly higher in group A than in group B (33.3 vs 6.7%, chi2 = 5.1, P = 0.023). Abnormal ECG changes were present in 10% and 6.7% in Group A and Group B, respectively. In Group A, one patient had peripheral vascular disease (PVD) while in Group B none had PVD. A comparison of sib pairs, matched for age, duration of diabetes and the level of metabolic control showed that there was strong familial clustering of diabetic kidney disease in south Indians with Type 2 diabetes. This was independent of the familial clustering of diabetes. Prevalence of other vascular complications were also higher in Group A.