Objective To investigate the effects of metformin, aerobic exercise alone or in combination on thevascular oxidative stress in type 2 diabetic rats. Methods Rat models of type 2 diabetes were established by feeding ahigh-fat diet combined with low dose streptozotocin (STZ). Rats were assigned into five groups: normal control (NC),diabetes control (DC), diabetes swimming (DS), diabetes metformin (DM), and diabetes metformin plus swimming(DMS). After undergoing the respective interventions for 8 weeks, indicators of vascular morphology, protein expression inthe vascular tissue, and serum indicators were tested by histopathology using HE staining, western blotting, and ELISA.Results All the DS, DM, and DMS groups showed decrease to different degrees in fasting blood glucose and insulinlevels. Compared with the DC group, the DS, DM, and DMS groups exhibited significant increases in the protein expressionof Nrf2 and HO-1, and exhibited a clear decrease in the expression of NOX4. The activities of SOD in the DS and DMSgroups were higher than in the DC group. MDA levels in the DM and DMS groups were lower than in the DC group. Theconcentrations of TNF-α and VCAM-1 were decreased to varying degrees in the DS, DM, and DMS groups. Conclusions Metformin and aerobic exercise may relieve vascular oxidative stress in type 2 diabetic rats, by regulating the balance between Nrf2 and NOX4.