Abstract: Serum concentration of cystatin C a marker of glomerular filtration has been associated with Cardiovascular Disease (CVD). The aim of this study was to evaluate cystatin C as a marker of diabetic kidney disease in normoalbuminuric diabetic patients without Chronic Kidney Disease (CKD). The study population consisted of 65 subjects with metabolic syndrome and 32 subjects free of metabolic syndrome (control group). HDL-C, LDL-C, blood urea, triglycerides, glucose, HbA1c, serum cystatin C and serum creatinine were measured in both groups. GFR was calculated in both groups using Cockrofta Gault equation. Metabolic syndrome presented higher cystatin C levels than normal samples (0.98 8 0.26 1.24 8 0.24 p<0.05). In the binary logistic regression, the presence of diabetes and metabolic syndrome was significantly associated with elevated cystatin C levels. Diabetic patients also presented a slightly greater creatinine (1.11 8 0.09 1.04 0.15 p<0.05). The results suggest that cystatin C may be a marker for metabolic syndrome and may identify a certain degree of renal dysfunction even when serum creatinine does not exceed normal level.