Recently evidence has accumulated that diabetic nephropathy clusters in families, both in insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetic patients. Furthermore, hypertension and cardiovascular accidents are found more frequently in families of NIDDM with diabetic nephropathy. Some observations in offspring of NIDDM patients with diabetic nephropathy point to high urinary albumin excretion and slightly greater blood pressure values, both within the normal range compared to offspring of patients without diabetic nephropathy. Further follow-up is required to assess whether these findings are indicative of a possible genetic predisposition to diabetic nephropathy.