Male albino rats with diabetes induced by the administration of streptozotocin (STZ) (45 mg/kg, i.v.) were treated with oral administration of diphenyl diselenide (DPDS) pre-dissolved in soya bean oil. A significant reduction in blood glucose levels was observed in STZ-induced diabetic rats treated with DPDS compared with an untreated STZ diabetic group. The pharmacological effect of DPDS was accompanied by a marked reduction in the level of glycated proteins, and restoration of the observed decreased levels of vitamin C and reduced glutathione (GSH; in liver and kidney tissues) of STZ-treated rats. DPDS also caused a marked reduction in the high levels of thiobarbituric acid reactive substances (TBARS) observed in STZ-induced diabetic group. Finally, the inhibition of catalase, delta aminolevulinic acid dehydratase (eth-ALA-D) and isoforms of lactate dehydrogenase (LDH) accompanied by hyperglycemia were prevented by DPDS in all tissues examined. Hence, in comparison with our earlier report, the present findings suggests that, irrespective of the route of administration and the delivery vehicle, DPDS can be considered as an anti-diabetic agent due to its anti-hyperglycemic and antioxidant properties.