Background Litsea cubeba (Lour) Pers. (Lauraceae) fruit has traditionally been used in treatment of diabetes in Sikkim, India. The purpose of the present study is to investigate the antidiabetic activity of methanol extract of Litsea cubeba fruit (MELCF) against streptozotocin (STZ)-induced diabetes in male albino mice. MELCF was assessed for in vitro α amylase, α glucosidase inhibitory activity and in vitro antioxidant activity against 2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide radicals. STZ was given intraperitoneally at 60 mg/kg for consecutive 3 days to mice. MELCF was administered orally in three doses 100 mg/kg, 200 mg/kg, 300 mg/kg body weight to STZ-induced mice. Metformin (200 mg/kg body weight) served as reference. Blood glucose and body weight were checked in seven days interval. After 28 days of treatment, the glycosylated hemoglobin (HbA1c), cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine, urea were measured. Hepatic and renal antioxidant parameters of viz. lipid peroxidation (LPO), reduced glutathione (GSH) and superoxide dismutase (SOD) were estimated. The histopathological evaluation of pancreas, liver and kidney was performed. Results MELCF demonstrated significant alpha-amylase, DPPH and nitric oxide inhibitory effects. It significantly reduced blood glucose in a dose dependent manner. It has normalizing effect on HbA1c, AST, ALT, TC, TG, urea and creatinine. It has a modulator effect on tissue antioxidant status i.e., LPO, GSH and SOD. Histopathological findings reveled regenerative effect in pancreatic islets, liver and kidney. Conclusion It can hence be concluded that, Litsea cubeba fruit has significant attenuative effect against diabetic complications in mice.