To clarify the hypoglycemic effects of tuber aqueous extracts of Dioscorea esculenta （Lour.） Burkill and D. polystachya Turcz.， effects of 10 and 20 g·kg^-1·d^-1 tuber aqueous extracts of D. esculenta ‘Tianyu No. 1’ and D. polystachya ‘Tiegun’ on body mass and blood glucose level of diabetic mice were assayed by taking 0.2 g·kg^-1·d^-1 metformin hydrochloride and 0.6 g·kg^-1·d^-1 Xiaoke pills as positive controls. The results show that after 3 weeks of intragastric administration with different doses of tuber aqueous extracts of ‘Tianyu No. 1’ and ‘Tiegun’， the average body mass of diabetic mice significantly increases， while the average blood glucose level significantly decreases； in which， compared with the diabetic model group， 20 g·kg^-1·d^-1 tuber aqueous extracts of ‘Tianyu No. 1’ and ‘Tiegun’ can increase the average body mass of mice by 17.6% and 18.1% respectively and decrease the blood glucose level by 23.0% and 22.3% respectively， and the promotion effect on body mass and the hypoglycemic effect of diabetic mice are close to those of positive controls. It is suggested that as medicinal and edible plants， tuber aqueous extracts of ‘Tianyu No. 1’ and ‘Tiegun’ can exert auxiliary hypoglycemic effects.