Three cases are presented in which biopsy-proven diabetic nephropathy was found in nephrotic patients with no prior history of diabetes. One patient presented with advanced retinopathy and end-stage renal disease (ESRD), another with retinopathy and mild renal insufficiency, and a third with mild renal insufficiency alone. In each case, biopsy showed diffuse and nodular glomerulosclerosis with no evidence of kappa or lambda light chains. The patients had normal fasting serum glucose values, and two had normal oral glucose tolerance tests. Twenty-three similar cases in the literature were reviewed, and in most, some evidence of diabetes or hyperglycemia was found; five cases remained in which there was no evidence of hyperglycemia at any time. The cases reviewed included a disproportionate number of men (65%) and blacks (42%). It is concluded that diabetic nephropathy may exist in the absence of detectable hyperglycemia in a small number of extraordinarily susceptible individuals. Men and blacks appear to be at increased risk.