The present study was carried out to analyze the chemical composition of Gymnema sylvestre leaves powder, to identify its total phenolic compounds, also investigate the hypoglycemic effects of different doses of Gymnema sylvestre  leaves aqueous extract (GAE) on  oxidative stress of diabetic rats . A total of  30 male albino rats weighing(150±5g)were used in this study. Rats were divided into two  main group .The first main group (6 rats) fed on basal diet (BD) as a negative control group (NC).The second main group(24 rats) was injected intra-peritoneally with asingle dose of streptozitocin at a dose of 60mg/kg body weight for induction of diabetes. The rats in this group divided into 4 subgroups (n = 6 each), subgroup (1) fed on basal diet, as a (positive control group). Subgroups (2, 3 and 4) fed on basal diet and treated orally with Gymnema water extract at (100 - 200 and 400 mg/kg b.wt/day) respectively. The chemical analysis of Gymnema sylvestre  leaves powder showed that each 100 grams contained The highest concentration of total carbohydrate (50.78%) followed by total fiber (14.93 %), total protein (12.8 %) and ash (9.9 %),while the lowest concentration was recorded for total fat (4.39 %).The total phenolic compound (5073.9 ppm gymnenic acid equivalent), has been identified by HPLC.
 
Oral treating to diabetic rats with different doses of GAE at (100,200 and 400 mg/Kg) improved the mean values of lipid profile, kidney functions, glucose, liver enzymes, malondialdhyde and glutathione peroxidase, as compared to the positive control group.GAE play an important role in decreasing the complications which were resulting from diabetes. In conclusion , Gymnema sylvestre extract has high effective antioxidant, hypoglycemic, hypolipidemic, hepatoprotective and nephroprotective effects in STZ-intoxicated rats. The hypoglycemic and antioxidant activity of GAE could be due to presence of many phenolic compounds detected in this study .