BACKGROUND: We evaluated serum protein electrophoresis and urine SDS-agarose gel electrophoresis (SDS-AGE) for protein in diabetic nephropathy patients to assess their diagnostic and prognostic value. METHODS: Fifty four cases of diabetic nephropathy (mean age, 60.9 (1-75) years; male, n=28; female, n=26) and control group (n=10) were studied. Random urine was analyzed by SDS-AGE. These were determined from the presence of low molecular weight and/or high molecular weight proteins by SDS-AGE. Serum protein electrophoresis, total protein, albumin, BUN, creatinine were measured. RESULTS: The patterns of proteinuria were glomerular (n=11), tubular (n=2), mixed (n=16), mixed-mostly glomerular (n=10), mixed mostly tubular (n=2), albumin only (n=13), Nine cases showed nephrotic syndrome pattern by serum protein electrophoresis. Mean serum total protein was 6.93+/-0.84 g/dL; albumin, 3.91+/-0.56 g/dL; BUN, 26.8+/-17.74 mg/dL; creatinine, 1.52+/-1.02 mg/dL. Compared to the control group, the albumin level of diabetic nephropathies was low, but the alpha 1 and alpha 2 globulin levels were high. A/G ratio was low and beta and gamma fractions showed no differences. CONCLUSIONS: Using SDS-AGE of proteinuria, various kidney damage patterns were observed. There were no specific findings in diabetic nephropathies by serum protein electrophoresis.