Abstract: Objective To investigate the relationship between Homocysteine (Hcy) and incipient diabetic nephropathy in type 2 diabetes mellitus (DM).Methods The plasma Hcy level was measured by high performance liquid chromatography with fluorescence detection in 67 patients with type 2 DM and 47 control persons,the plasma thrombomodulin(sTM),folate and vitamin B 12 were determined simultaneously.Results The plasma Hcy level was higher in type 2 DM patients than that in control subjects (15.27±6.04μmol/L vs 12.10±1.86μmol/L, P <0.01),and the plasma Hcy level was higher in incipient diabetic nephropathy patients than that in non nephropathy patients (17.86± 8.04 μmol/L vs 13.83±4.00μmol/L, P <0.01).Diabetic patients with hyperhomocysteinmia had a higher diabetic nephropathy incidence rate (52.0% vs 26.2% P <0.05) compared with noe hyperhomocysteinmia patients,and the former had higher sTM level than the latter ( P <0.05).Through the Logistic regression analysis,it was concluded that Hcy was related to the occurrence of incipient diabetic nephropathy.Conclusion Hyperhomocysteinemia is related to the occurrence of incipient diabetic nephropathy,and endothelial dysfuntion may be involved in its pathogenesis.