In this study, the inhibiting effect on a-amylase and a-glucosidase, the antioxidant activity of different fruit extracts from V. opulus and the chemical compounds in most active extract were investigated. The antioxidant activity was tested with -DPPH., -ABTS.+ and FRAP tests and the phytochemical analyses of the active extract was determined by LC- MS/MS. According to the results, the highest a-glucosidase and a-amylase activity even from positive control acarbose were found in ethanol extract -(IC50 = 3.671 +/- 0.016 mu g/mL and 601.667 +/- 0.015 mu g/mL, respectively). Also, the highest TPC (96.000 +/- 0.001 mgGAE/gextract) and TFC (69.327 +/- 0.693 mgCA /gextract) was found in the same extract and this extract showed the highest antioxidant activity on -DPPH. (%34), FRAP (at a concentration of 1 mg/mL equivalent to 1521.527 +/- 1.528 mmol -Fe2+) and -ABTS+. (at a concentration of 0.5 mg/mL equivalent to 0.43 +/- 0.002 mu M Trolox) tests. Organic and phenolic acids and triterpenic compounds were identified in V. opulus ethyl acetate extract by LC-MS/MS analysis. In conclusion, this study may be supported with detailed investigation on different pathways in anti-diabetic activity and could contribute to the advanced studies of this species.