Objectives: The aim of present study was to investigate recovery effects of Hirudo, which has been used clinically in diabetes therapy. Methods: We established three groups: normal, control, Hirudo, and assigned 6 rats to each group. The normal group was not treated by any process and fed by normal saline. The control & Hirudo groups were administered streptozotocin (STZ) to induce diabetes. Hirudo extract was orally administered to the Hirudo group for 10 days. After 8 weeks, the rats were sacrificed and their body weight, 24hrs urinary protein excretion, glucose, albumin, BUN, creatinine, total-cholesterol, LDL-cholesterol, triglyceride in blood, and level of glycation end-product (AGE) and transforming growth factor (TGF-${eta}1$) in serum were measured. Morphological profiles and morphometric studies of the kidney cortex, renal transforming growth factor (TGF-${eta}1$) expression, and renal receptor for advanced glycation end-products (RAGE) expression were studied. Results: The following results were obtained. The protein amount in urine per 24hrs of the Hirudo-treated group as compared to the control group was significantly reduced. The BUN and creatinine level in serum of the Hirudo-treated group as compared to the control group was significantly inhibited. The construction change in kidney of the Hirudo-treated group as compared to the control group was significantly inhibited. The factor of the Hirudo-treated group as compared to the control group was significantly inhibited, which induced the construction change in kidney. Conclusions: The above results suggest that Hirudo partially improved the function of the kidney.