Many traditional plants have been used to fight life-threatening diseases such as diabetes. These plants have been shown to possess antioxidant activities, improving the diabetes inconveniences. Wister albino rats were become diabetic by streptozotocin (STZ) induction. The effect of 200 mg/kg ethanolic extracts of either Cinnamomum zeylanicum bark (CZ) or Syzygium cumini seeds (SC) were investigated on STZ-induced diabetic rats. The impact of CZ or SC administration was
observed. Blood glucose, insulin level, hemoglobin content, lipid profile, liver and kidney functions, and antioxidant enzymes in plasma were evaluated. Diabetic rats exhibited an increase in the levels of blood glucose, total cholesterol, triglycerides and low density lipoprotein cholesterol (LDLcholesterol). In contrast, the levels of insulin and high density lipoprotein cholesterol (HDLcholesterol) were diminished. The oral administration of CZ and SC showed a decrease in glucose level, total cholesterol,
triglycerides, and LDL- cholesterol, whereas an increase in insulin level and HDL-cholesterol were recorded. What's more, the antioxidant enzymes in diabetic control rats showed significantly abnormal activities of low superoxide dismutase (SOD), catalase (CAT), glutathione peroxide (GPx) activities and reduced glutathione (GSH)) compared to treated diabetic rats. Also, in the extent of lipid peroxidation (LPO). Both CZ and SC possessed antioxidant activity as shown by elevated SOD and GPx activities and reduction in LPO. CZ and SC are functioning to improve the level of insulin, hyperglycemia, hyperlipidemia, oxidative stress and kidney and liver dysfunctions in STZ-induced diabetic rats.