Aims. This study was designed to investigate the enzyme inhibitory and antidiabetic activity for the constituents isolated fromDillenia indica.Methods. The leaves ofD. indicawere extracted with methanol and subjected to fractionation and chromatographic separation, which led to the isolation of seven compounds: betulinic acid (1), n-heptacosan-7-one (2), n-nonatriacontan-18-one (3), quercetin (4),βsitosterol (5), stigmasterol (6), and stigmasteryl palmitate (7). Among these isolates, compounds1,4,5, and6were evaluated forin vitroenzyme inhibition and compounds4,5and6were evaluated for antidiabetic activity in streptozotocin-nicotinamide induced diabetic mice.Results. Compounds1,4,5, and6showed 47.4, 55.2, 48.8, and 44.3%α-amylase inhibition, respectively, and 52.2, 78.2, 52.5, and 34.2%α-glucosidase inhibition, respectively, at the dose of 50 µg/kg. Compounds4,5and6also showed significant (*P<0.05) antidiabetic activity in streptozotocin-nicotinamide induced diabetic mice at the dose of 10 mg/kg.Conclusion.These results provide evidence thatDillenia indicamight be a potential source of antidiabetic agents.