Mixture of Cleistocalyx operculatus leaves, guava leaves, lotus leaves (VOS) is determined with high polyphenol content (320mg/g) and their ability of inhibition alphaglucosidase and their ability to eliminate free radicals were assessed. In this study, the authors determined the toxic dose levels of VOS in mice and investigated the efficacy of blood glucose controlling in diabetic mice. The results showed the toxic dose levels of VOS not determined yet, even at high doses age of 30g/kg body weight. After 8 weeks of administration with 200 mg VOS/kg body weight and 400 mg VOS/kg body weight, VOS diabetic mice had significantly reduced blood glucose level as compared to control diabetic mice. VOS diabetic mice with 400 mg dosage are lower in blood glucose levels than that of the diabetic mice with 200 mg. Also, the significant reducing in HbA1c was observed in VOS diabetic mice as compared with control diabetic mice. VOS-product extracted from Cleistocalyx operculatus leaves, guava leaves, lotus leaves might be considered as a safe product and to be a potential product in the supporting of prevention and treatment of diabetes.