Chronic uncontrolled hyperglycaemia leads to increased oxidative stress and lipid peroxidation resulting in vascular complications and accelerates the progression of diabetic atherosclerosis. Though varieties of modern drugs used in the treatment of diabetes, the complications of diabetes are increasing. Naringenin (NG), has been reported to have potent antioxidant and anti-atherosclerotic properties. However, the effects of NG as vasculoprotective agent in prolonged hyperglycaemia are not well documented. Thus, this study was aimed to determine the effect of NG against vascular changes after prolonged hyperglycaemia in a diabetic rat model. Thirty adult male Sprague-Dawley rats were induced with fructose and streptozotocin to develop the diabetic rat model. After 4 weeks, the rats were randomly divided into 5 groups each group consisting of 6 animals: control, control treated with NG, non-treated diabetes mellitus (DM), DM treated with NG and metformin-treated DM. The treatment with NG (50 mg/kg) and metformin were continued for 5 weeks. The results showed that consumption of NG at 4 weeks post diabetic did not improved blood sugar, blood pressure and serum lipid profile. However, NG did significantly improve oxidative stress parameters in the aortic tissue like malondialdehyde (MDA). Analysis through light microscopy and transmission electron microscope (TEM) reverted the histological changes caused by prolonged hyperglycaemia. The findings thus demonstrated that introduction of NG after prolonged exposure to hyperglycaemia improved the vascular deterioration in diabetic group by decreasing oxidative stress evident by the reduced in the lipid peroxidation activity. Thus, this study showed the potential use of NG as adjunct in managing the diabetic condition during late presentation.