The absence of scientific data on the age long folkloric use of Digitaria exilis grains by sufferers of diabetes prompted the present investigation. This study was aimed at evaluating the antidiabetic activity of aqueous extract of Digitaria exilis grains in streptozotocin (STZ)-induced diabetic rats . Forty two male rats (166.43 ± 3.32 g) were completely randomized into six groups (A-F) of 7 animals each. Animals in group A (control) were administered 0.5 ml of distilled water while those in groups B, C, D, E and F which were induced with diabetes mellitus (by intraperitoneal administration of 60 mg/kg body weight of STZ) were also administered distilled water, 50 mg/kg body weight of metformin (a reference antidiabetic drug), 50, 100 and 200 mg/kg body weight of aqueous extract of D . exilis grains respectively, twice daily for 14 days. Blood glucose levels and some relevant biomolecules were determined 14 days post-administration. Alkaloids, flavonoids , saponins , tannins , anthraquinones, terpenoids , cardiac glycosides , phlobatannins , phenolics and cardenolides were detected in the extract with alkaloids (30.20 mg/ml) occurring the most and phlobatannins (0.22 mg/ml) the least. Streptozotocin significantly (p < 0.05) increased the levels of blood glucose, serum albumin , urea, creatinine and cholesterol, activities of glucose-6-phosphatase and fructose-1,6-bisphosphatase in the liver and intake of feed and water. Body weight, weight of pancreas, pancreatic insulin, liver glycogen content, red blood cell and white blood cell and their related indices, liver hexokinase and phosphofructokinase activities were significantly reduced by STZ. In contrast, the extract significantly reversed all those STZ-treatment induced changes with the 200 mg/kg body weight of the extract producing profound values that compared favourably with the distilled water treated non-diabetic animals and metformin treated diabetic animals. Overall, this study revealed that Digitaria exilis grains possess antidiabetic activity via incre...