Semecarpus anacardium Linn. nut milk extract (SA) was evaluated for its antidiabetic role in type 2 diabetic rats. Type 2 diabetes was induced in rats by feeding high-fat diet for 2 weeks followed by single intraperitoneal injection of streptozotocin 35 mg/kg body weight. Diabetic rats were treated with SA orally at a dosage of 200 mg/kg body weight daily for 30 days. Metformin (500 mg/kg body weight, orally) was used as a reference drug. SA significantly (p < 0.05) reduced the blood glucose levels and decreased the levels of HbA1c and the glucose intolerance. SA treatment significantly (p < 0.05) decreased the increase in lipid profile. The levels of urea, uric acid and creatinine were restored to near normal levels when compared with control diabetic rats. The histopathological abnormalities were also found to be normalized after treatment with SA nut milk extract. The potential antihyperglycemic action of SA is plausibly due to its underlying antioxidant role.