Cecropia obtusifolia is widely used in Mexican traditional medicine due to its reputed hypoglycemic effect. During a period of 32 weeks, aqueous extracts of the leaves of this plant were administrated daily to 12 recently diagnosed type 2 diabetic patients, controlled only with diet and exercise. Serum glucose, cholesterol, triglyceride and insulin levels were determined every 15 days; HbA1c, ALT, AST and ALKP were measured every month. A significant reduction of glucose was detected after 4 weeks of administration but the reduction was significant and sustained after 18 weeks of administration. The HbA1c was also significantly reduced after 6 weeks of treatment. No significant changes on cholesterol, triglycerides ALT, AST, ALKP or insulin could be detected. No collateral effects were observed. After suspending the administration of the extract, and a follow-up of 34 weeks, the glucose and HbA1c levels increased reaching levels higher than the basal ones. It can be concluded that the aqueous extracts of Cecropia obtusifolia have a significant hypoglycemic effect with no adverse effects and that the mechanism of action is not brought about by stimulating the insulin secretion. The results support the fact that the extracts of Cecropia obtusifolia have a great potential to be further developed into a phytomedicine.