Diabetes mellitus (DM) is recognized as a serious global health problem that is characterized by high blood sugar levels. Type 2DM is more common in diabetic populations. In this type of DM, inhibition of -glucosidase is a useful treatment to delay the absorption of glucose after meals. As a megabiodiversity country, Indonesia still has a lot of potential unexploited forests to be developed as a medicine source, including as the -glucosidase inhibitor. In this study, we determine the -glucosidase inhibitory activity of 80 ethanol extracts of leaves and twigs of some plants from the Apocynaceae, Clusiaceae, Euphorbiaceae, and Rubiaceae. Inhibitory activity test of the -glucosidase was performed in vitro using spectrophotometric methods. Compared with the control acarbose (IC 50 117.20μg/mL), thirty-seven samples of forty-five were shown to be more potent α-glucosidase inhibitors with IC 50 values in the range 2.33112.02μg/mL.