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In this study, polyphenols were extracted from different parts (seed husks, seeds, young and old leaves) of Toona sinensis collected from Taihe District, Anhui province, China, through ultrasound-assisted extraction. During in vitro experiments, seed husks polyphenol extracts exhibited inhibitory effects against α-amylase and α-glucosidase up to 89% and 86.7%, respectively, and these values were slightly lower than the inhibitory rates of acarbose (91% and 90.5% on each enzyme) at the same concentrations. During in vivo experiments, treatment with high-dose seed husks polyphenol extracts (120 mg/kg body weight) significantly reduced the blood glucose levels, increased the glucose tolerance and insulin tolerance of diabetic mice (P < 0.05); In addition, the contents of triglyceride, total cholesterol, non-esterified fatty acid, high-density lipoprotein cholesterol and low density lipoprotein cholesterol in serum could be reduced, and the influence on total cholesterol was significantly different (P < 0.01). Moreover, the activity of superoxide dismutase and glutathione could be Obviously improved, the content of malonaldehyde could be reduced in serum, among those the effect on glutathione enzyme was extremely significant (P < 0.01). The results showed that the seed husks polyphenol extracts from T. sinensis had obvious hypoglycemic effect, and the mechanism of hypoglycemic might be related to the improvement of insulin sensitivity by repairing damaged islet cells. Meanwhile, antioxidant enzyme activity was improved, oxidative stress injury was reduced, and lipid metabolism was enhanced. [ABSTRACT FROM AUTHOR]