The antidiabetic effects of Mung bean sprout (MBS) extracts and Mung bean seed coat (MBSC) extracts were investigated in type 2 diabetic mice. Male KK-A (y) mice and C57BL/6 mice were used in this study. In KK-A (y) mice, the blood glucose, plasma C-peptide, glucagon, total cholesterol, triglyceride, and blood urea nitrogen (BUN) levels were significantly higher than those in the C57BL/6 mice ( P < 0.001, P < 0.001, P < 0.01, P < 0.001, P < 0.01, and P < 0.01). In addition, KK-A (y) mice showed an obvious decrease in insulin immunoreactivity in pancreas as well. MBS and MBSC were orally administrated to KK-A (y) mice for 5 weeks. It was found that MBS (2 g/kg) and MBSC (3 g/kg) lowered blood glucose, plasma C-peptide, glucagon, total cholesterol, triglyceride, and BUN levels and at the same time markedly improved glucose tolerance and increased insulin immunoreactive levels. These results suggest that MBS and MBSC exert an antidiabetic effect in type 2 diabetic mice.