Abstract: AIM: To study the protective effect and mechanism of swimming on kidney of diabetic mice.  METHODS: The mice were randomly divided into normal control group, normal swimming group, type 2 diabetes mellitus (T2DM) mice model group, diabetic swimming group and metformin group. T2DM model was established by streptozotocin (STZ) method. The mice in normal swimming group and diabetic swimming group were given swimming exercise (1 h a day), and the metformin group were given metformin (200 mg/kg) by gavage once a day for 7 weeks. Fasting blood glucose and serum insulin were measured and insulin resistance index was calculated. The contents of uric acid, urea and creatinine in serum were determined. The ratio of renal mass to body mass was calculated, and the pathological changes of renal tissues were observed. The relative expressions of autophagy related proteins LC3 and P62 in renal tissues were detected by Western blot. RESULTS: Compared with normal control group, insulin resistance index and renal mass/body mass ratio in model group were significantly increased. Serum uric acid, urea and creatinine levels increased, and glomerular pathological changes were obvious. LC3II/LC3I ratio decreased significantly. The expression of P62 was significantly increased. Compared with model group, insulin resistance index and renal mass/body mass ratio in diabetic swimming group were significantly decreased. The contents of serum uric acid, urea and creatinine decreased, and the pathological changes of glomerular were alleviated. LC3II/LC3I ratio increased significantly. The expression of P62 decreased significantly (P even <0.05). CONCLUSION: Swimming protects the kidney injury of T2DM mice, and its mechanism may be related to promoting the autophagy process of renal tissue.

Key words: swimming, diabetic mice, kidney injury, autophagy, metformin