Experimentally induced diabetic rats were treated separately with insulin and vanadate. The activities of hexokinase (HK) and glucose-6-phosphate dehydrogenase (G-6PDH) were increased in reticulocyte hemolysate isolated from the diabetic rats and were restored to normal levels by insulin. The restoration was not detected in vanadate treated diabetic animals. The enzymes of glutathione metabolism namely glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-s-transferase (GST) exhibited increases in their activities with diabetes and were restored to almost control values by insulin treatment. Vanadate given to diabetic animals further increased GPx, and GST. The level of superoxide dismutase(SOD) decreased in the reticulocytes of diabetic rats and catalase (CAT) was unchanged. Both CAT and SOD had normal values when the diabetic rats were treated with insulin and vanadate. It is proposed that vanadate may cause an increase in the activity of GR which may stimulate glucose transporters and glucose metabolism.