Diabetic nephropathy is one of the common causes of native kidney dysfunction. Total number of 50 subjects will be enrolled in this present cross sectional study in the department of General Medicine, Chengalpattu medical college and hospital, in collaboration of Radiology and Nephrology of the same institution during two years aim to evaluate the diagnostic usefulness of renal resistive index by duplex Doppler ultrasonography for detection of renal dysfunction in diabetic patients. Clinically diagnosed diabetic patients having diabetic nephropathy are taken as a sample. The results are that there is a strong positive association between microalbuminuria and resistive index.A positive correlation (r=0.581, p<0.01) was found between resistive index with serum creatinine and albuminuria which indicates deterioration of renal function, i.e. progression of the disease. In previous study it was shown that the correlation between serum creatinine and RI values in diabetic nephropathy to be (r=0.84) indicating that RI may be useful as a renal prognostic marker.In this regard, even if renal function is well preserved at baseline when RI is greater, we should observe these patients carefully in the follow-up period because they have significant vascular lesions