Early detection of deterioration or impairment in renal function is critical in management of diabetic patients. Serum cystatin C may be the most sensitive indicator of glomerular filtration rate (GFR) in a clinical environment.We compared cystatin C with creatinine, the Cockcroft-Gault (C-G) In
our study population, cystatin C (P<0.001) was better correlated with glomerular filtration rate (GFR) (r=0.922) than were creatinine (r=743), Cockcroft-Gault (C-G)formular (r=0.755) and Modification of Diet in Renal Disease (MDRD) equation (r=0.818). Mean cystatin C concentrations showed step wise statistically significant increases as GFR reduces, allowing very early identification of reduction in renal function. At 90ml/min/1.73m2 and 75ml/min/1.73m 2 cut-points, diagnostic efficiencies of cystatin C (90% and 93%) were better than those of the other variables (80%-84% and 86%-89%, respectively; P = 0.01).All data supported the value of serum cystatin C compared with conventional estimates based on serum creatinine measurement for detecting very early reduction of renal function. Use of cystatin C to measure renal function will make for early detection, prevention, and treatment of diabetic nephropathy in type 2 diabetics.