Five mulberry leaf extracts (water, 25, 50, 75, and 100% EtOH) were characterized for in vitro hypoglycemic activity and chemical profiles. According to chemical profiles obtained from $^{15}Tesla$ Fourier transform ion cyclotron resonance mass spectrometry, water extracts contained more 1-deoxynojirimycin (DNJ) and fewer phytochemicals than other extracts. However, water extracts showed the highest inhibitory activity of glucose uptake. The degree of inhibition of ${alpha}$-glucosidase activity was similar for all extracts. The effect of mulberry leaf extracts on the glucose metabolism may be attributed to additional or cooperative effects of DNJ with other phytochemical compounds.