Background: diabetes mellitus is the most common endocrine disease, which is considered one of the most important causes of morbidity and mortality worldwide. Diabetes can affect many different organ systems in the body and can lead to serious complications. These complications can be classified as microvascular or macrovascular. Microvascular complications include nervous system damage, renal system damage and eye damage. Macrovascular complications include cardiovascular disease, stroke and peripheral vascular disease. Objective: it aimed to assess effects of  aqueous mango leaves extract on diabetes mellitus. Materials and Methods: aqueous mango leaves extract were assessed for their effects on blood glucose, blood pressure, lipid profiles and body weight in diabetic rats. Also, check out photochemical agents including total phenolics, flavonoids, tannins and antioxidant activity in the aqueous mango leaves extract. Results: aqueous mango leaves extract are rich in total phenols, flavonoides and tannins content, so the antioxidant activity is high. Random blood glucose level and systolic blood pressure were decreased in diabetic rats treated with either aqueous extract of mango leaves or glibenclamide, while, body weight was increased in diabetic rats treated with either glibenclamide or aqueous extract of mango leaves. The contractile responses to norepinephrine were decreased and the relaxant effect of acetylcholine were increased significantly in diabetic rats treated with either glibenclamide or aqueous extract of mango leaves. The treatment of glibenclamide with aqueous mango leaves extract gave the best results with diabetic rats compared to other treatments. Conclusion:  aqueous mango leaves extract produced a significant hypoglycemic effect in diabetic rats and improved the diabetes mellitus induced changes in the vascular reactivity, so possibility of its usingas dietary supplements have healthy and therapeuticproperties.