Abstract: Background and Objectives: Diabetes mellitus is a metabolic disease that is on the increase globally in recent years. Viburnum foetidum is a medicinal plant used in traditional medicine for the treatment of various diseases. In this study, the antidiabetic effect of Viburnum foetidum bark ethanolic extract (VFE) and ethanolic extract fractions (n-butanol, ethyl acetate and n-hexane) were evaluated using both in vitro (RIN-5F and HepG2 cells) and in vivo (glucose loaded [10 g kg–1] and streptozotocin [60 mg kg–1] induced diabetic Wistar rats) models. Materials and Methods: In the in vivo studies, 100, 200 and 400 mg kg–1 Viburnum foetidum bark ethanolic extract and 200 mg kg–1 of each extract fractions were administered to streptozotocin (60 mg kg–1) induced diabetic Wistar rats. Non toxic mass value of Viburnum foetidum extract was used in the in vitro (0.625, 1.25 and 2.5 μg/100 μL) and in vivo (100, 200 and 400 mg kg–1) studies. Results: Viburnum foetidum extract and extract fractions increased RIN-5F insulin secretion and HepG2 glucose uptake when compared with untreated cells. Whereas, in 21 days treated diabetic rats, the extracts caused a decrease in fasting blood glucose level, increase in serum insulin and serum α-amylase level when compared with the untreated rats. The ethyl acetate extract fraction at 200 mg kg–1 exerted a more increase in RIN-5F cells insulin secretion, HepG2 cells glucose uptake, serum insulin and serum α-amylase level than other extract fractions. Conclusion: Viburnum foetidum bark exerts its antidiabetic effect by enhancing insulin secretion by pancreatic cells, increasing glucose uptake by liver cells and enhancing the pancreas functionality thereby increasing serum insulin and serum α-amylase level.