Background: Metformin  is the first-line treatment for T2DM especially in obese or overweight diabetic patients. The aim of the present study was to evaluate the effect of metformin monotherapy on body weight, glycaemic control, lipid profile,  oxidative  stress and cardiac injury in type 2 diabetic rats. Methods: Rats were classified into Three groups; control, diabetic and Diabetes + Metformin. Diabetes  was induced  by receiving high-fat diet for 2 weeks followed by intraperitoneal injection of streptozotocin. Metformin was given orally for 28 days after confirmation of diabetes. Serum glucose, insulin, lipid profile, cardiac injury markers and oxidative stress markers (MDA and TAC) were measured and heart histopathology was done. Results: The diabetic group showed significantly elevated serum levels of glucose, cardiac injury markers and MDA with disrupted lipid profile along with histopathological features of cardiac tissue injury and significantly decreased serum levels of insulin and TAC in comparison with control group. Treatment with metformin produced significant decrease in both food intake and body weight and significantly decreased serum levels of glucose, cardiac injury markers and MDA, besides significantly elevated serum levels of insulin and TAC with improvement of the lipid profile and the histopathological picture  in comparison with  the diabetic group. Conclusion: Metformin produces beneficial changes regarding weight, food intake, glycaemic control, hypoinsulinemia, hyperlipidemia and cardiac and oxidative injury along with improved cardiac histopathological picture.