One of the potential anti-diabetic natural plant is surian (Toona sinesis Merr.). Wood from T. sinensis contains several flavonoid compounds such as catechins, epicatechins, and procyanidins, which have inhibitory activity of the a-glucosidase enzyme. This enzyme plays a role in the mechanism of the occurrence of diabetes mellitus. In-vivo test results using mice showed a skin extract surian with a dose of 150 mg / kg BW can lower blood sugar levels to 72%, better than the drug Glibenklamid which only 31%. Surian skin extract can also improve pancreatic ß cells as insulin producer.