The plasma TGF-β level, alone with ADMA, provided better prediction value than the more direct glomerular filtration indicator cystatin C. In our previous study, we found that TGF-β pathway genes were highly expressed in the kidneys of very early stage diabetic nephropathy renal biopsies, long before renal fibrosis and decreased filtration occurred. The gene discussed is TGFB1; the disease is diabetic kidney disease.