Use of Serum Cystatin C in Assessment of Early Deterioration of Renal Function in Type 2 Diabetic Industrial Workers in Port Harcourt, Nigeria

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) formular, and the Modification of Diet in Renal Disease (MDRD) equation for the assessment of early decreased renal function in 50 type 2 diabetic patients with and without significant renal impairment (GFR; 8-205 ml/min/1.73m 2 ).Relationships of cystatin C, creatinine, and iohexol clearance were linearized using simple regression model and diagnostic efficiency calculated. 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/1.73m 2 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.