Abstract: Diabetes mellitus is a metabolic disorder and emerging pandemic of the 21st century. Piperine, the chief alkaloid present in Piper nigrum (black pepper), has a wide array of uses in alternative and complementary therapies. The effect of piperine on blood glucose level was studied in alloxan-induced diabetic mice in acute and subacute study models. Piperine was isolated from the fruits of Piper nigrum crude extract. Diabetes was induced using alloxan in albino mice which were then randomly divided into 5 groups (n = 6). In acute study, drugs were administered orally as: control (2% gum acacia, 10 mL/kg), standard (metformin 150 mg/kg), P10 (piperine 10 mg/kg), P20 (piperine 20 mg/kg) and P40 (piperine 40 mg/kg). Drug intervention for subacute study consisted of once daily oral administration for 14 days of 2% gum acacia 10 mL/kg, metformin 250 mg/kg, and piperine 5, 10 and 20 mg/kg, respectively, in the control, standard and P5, P10, P20 groups. Blood glucose levels were estimated before and at 1, 2, 3 and 4 h post dosing, respectively, in the acute study and on day 7 and 14 in the subacute study. Results of acute study showed that at 2 h post-dosing piperine at high dose of 40 mg/kg showed significant rise in blood glucose level (p < 0.05) in comparison to control group. In contrast, a significant blood glucose lowering effect was seen with piperine at dose of 20 mg/kg on day 14 (p < 0.05) in the subacute study. In summary, we suggest that subacute administration of piperine has statistically significant antihyperglycemic activity while acutely it raises blood glucose at high doses. Further investigations are needed to consider it as prospective anti-diabetic agent at appropriate dosage.