Objective To retrospectively analyze the pathological characteristics of type 2 diabetes mellitus (DM) combined with primary renal diseases.   Methods Forty-nine patients with type 2 DM and renal lesions visiting our department between January 2004 and August 2007 were included. The included criteria were as follows: the history of type 2 DM less than 5 years

without retinal changes

progressive renal aggravation

gross hematuria or unparalleled massive proteinuria in a short time

without other secondary diseases. Their renal histological characteristics

the relationship of clinical symptoms and histological characteristics with their diagnosis and treatment were analyzed.   Results Forty-three out of 49 (87.76%) DM patients were with primary renal diseases of various pathological characteristics. The same clinical symptoms of type 2 DM patients combined with primary renal diseases might have different renal histological changes. Based on controlling the glucose in normal range

most of the patients got remission after receiving corticosteroids and/or some immune depressant.   Conclusion The renal histological characteristics definitely diagnosed by renal biopsy can well decide the diagnosis and treatment of type 2 DM combined with primary renal diseases.