OBJECTIVE: To examine the renal function changes and mechanisms on rats with diabetes through a sleeve gastrectomy operation. METHODS: Thirty-six rats were induced diabetes through injection of streptozotocin (STZ), and 30 of these diabetic rats that blood glucose levels at the midrange (blood sugar 17.88-23.65 mmol/L, mean: 20.32 mmol/L) were randomly assigned to the sleeve gastrectomy group, Sham-operation group and control group. The serum creatinine, lipid parameters were measured postoperatively. The 24 h urine volume obtained and urine albumin excretion rate (UAER) was calculated. Serum and urinary creatinine were examined and glomerular filtration rate (GFR) was counted. Kidney sections were stained with periodic acid-Schiff, and then the index of mesangial expansion was determined. The expression of synaptopodin for podocytes was also performed through the immunohistochemical procedure. A one-way ANOVA and t-test were performed to evaluate differences between groups and each other. RESULTS: Only one rat of SG group died after operation. The GFR ((8.44 ± 2.10) ml · g⁻¹ · d⁻¹), 24 h UAER ((36.04 ± 11.10) mg/d), plasma lipids level (total cholesterol (1.66 ± 0.23) mmol/L, triglycerides (1.25 ± 0.17) mmol/L), kidney weight ((1.61 ± 0.06) g), the index of mesangial expansion ((6.14 ± 1.50)%) and synaptopodin expression ((20.44 ± 2.99)%) were improved in the SG group compared with the sham-operation group ((15.05 ± 3.01) ml · g⁻¹ · d⁻¹, (57.01 ± 11.34) mg/d, (2.15 ± 0.29) mmol/L, (1.65 ± 0.23) mmol/L, (1.93 ± 0.07) g, (11.32 ± 2.09)%, (10.34 ± 1.43)%) and control group ((14.79 ± 2.38) ml · g⁻¹ · d⁻¹, (62.71 ± 16.46) mg/d, (2.23 ± 0.21) mmol/L, (1.59 ± 0.20) mmol/L, (1.91 ± 0.06) g, (10.82 ± 1.79)%, (11.13 ± 2.43)%) (t = 0.781-5.025, all P < 0.05). CONCLUSION: The sleeve gastrectomy procedure can improve the renal function in a diabetes rat model may be through protecting the podocytes function and preventing the mesangial expansion of glomeruli.