Moderately increased albuminuria is widely accepted as the first clinical sign of diabetic nephropathy. However, previous morphometric studies and the autopsy study by Klessens et al. have clearly demonstrated that by the time moderately increased albuminuria is evident, the kidneys in some diabetic patients have already undergone glomerular and tubulointerstitial damage, which indicates that it is not a sensitive marker for diabetic nephropathy. Hence, there is a need for new biomarkers of early diabetic nephropathy.