To determine  the association of plasma copeptin, a surrogate of vasopressin, with the incidence of Diabetic Nephropathy  in Type 2 diabetes mellitus. Early detection of individuals having the highest risk could help avoid this complication. 60 patients with type 2 diabetes mellitus and 20 apparently healthy subjects serving as control were included. Plasma levels of Copeptin  and other biochemical parameters were determined. The correlation between copeptin and estimated glomerular filtration rate (eGFR) was investigated. There was a significant association between elevated copeptin concentrations and eGFR decline ( P= 0.001). High plasma levels of copeptin were associated with lower ACR (P <  0.001). As copeptin is emerging biomarker in diagnosis of many diseases ,our results suggest that copeptin  could be a useful prognostic marker for kidney function decline in type 2 diabetic patients and by this  eventually help prevent kidney complications.