Abstract: Objective To investigate tubular interstitium damage in patients with type 2 diabetes mellitus by measuring tubulointerstitium marker proteins.Methods 24 hour urinary albumin excretion (UAE)、retinol binding protein、α 1 microglobulin (α 1 MG)、β 2 microglobulin (β 2 MG)、Tamm Horsfall glycoprotein (THP)、urinary glucose (UG) and creatinine clearance rate (Ccr) were measured in 215 patients with type 2 diabetes mellitus.Results ①The raised prevalence rates of 24hURBP、24hUα 1 MG and 24hUβ 2 MG in 215 diabetic patients were 39.5%、45.1%、34.4%,respectively,and all the indexes increased with the increase of 24hUAE.The prevalence rate of decreased 24hUTHP was 40.0% ;②Among the patients with micro and macro albuminuria,Ccr in patients with raised 24hUα 1 MG decreased significantly in comparison with the patients with normal 24hUα 1 MG, P <0.05;③24hURBP、24hUα 1 MG、24hUβ 2 MG and 24hUTHP had no relationship with 24hUG.Conclusion The tubulointerstitium damage was rather common in type 2 diabetics except diabetic glomerulosclerosis,even earlier than glomerulus damage and may contribute to a certain extent to the reduction of renal function.