The present investigation is aimed to evaluate the antidiabetic activity of leaf extracts of Gardenia gummifera L. f. studies were carried out in normal and alloxan induced diabetic rats treated with methanolic leaf extracts of G. gummifera in 200mg/kg and 400mg/kg doses where Glibenclamide was used as standard drug. The test groups produced a significant increase in High Density Lipoprotein, Super Oxide Dismutase, Catalase, Reduced Glutathione and Glutathione Peroxidase levels; significant decrease in Total Cholesterol, Triglyceride, Low Density Lipoprotein, Very Low Density Lipoprotein, Lipid Peroxidation levels over diabetic control. The above results represent the effect of test drugs in the lipid profile and antioxidant properties of the test animals. Studies on histopathology of liver and kidney tissues of the test animals also provided the further support to the results. Overall result showed dose dependent effect. On conclusion the study provided the scientific evidence for the enthnomedicinal use of G. gummifera in the treatment of Diabetes Mellitus.