The present study was designed to determine the possible modulation of the pharmacological effect of metformin by pyridoxine in diabetic rats. Male wistar rats were made diabetic with a single injection of streptozotocin (45 mg/kg, i.p.). The rats with blood glucose level (BGL) greater than 200 mg/dl were considered as diabetic rats. Rats were divided into five groups: Group-1: Control rats; Group-2: Diabetic rats; Group3: Metformin (10 mg/kg/day p.o for 14 days) treated rats, Group-4: Pyridoxine (50 mg/kg/day i.p. for 14 days) treated rats, Group-5: Pyridoxine (50 mg/kg/day i.p. for 14 days) + Metformin (10 mg/kg/day p.o for 14 days) treated rats. After 14 days of treatment, diabetic rats showed significant increase in BGL, depression-related behavior, MDA level but decreased plasma nitrite level. Metformin treatment significantly abolished BGL, differentially modulated the depression-related behavior in TST and FST, and increased the plasma nitrite and MDA level of diabetic rats.