Oral vanadium administration to streptozotocin-diabetic rats has marked negative side-effects which are independent of the form of vanadium used.

In the present investigation, the effects of oral administration of sodium metavanadate, sodium orthovanadate and vanadyl sulphate to alleviate some signs of diabetes in streptozotocin-treated rats have been evaluated. Streptozotocin-induced diabetic rats drank aqueous solutions (NaCl, 80 mM) containing sodium metavanadate (0.15 mg/ml), sodium orthovanadate (0.23 mg/ml), or vanadyl sulphate pentahydrate (0.31 mg/ml) for 28 days. The vanadium-treated animals were compared to controls, either diabetic or nondiabetic, receiving drinking water containing NaCl (80 mM) only. Daily food and fluid intake were significantly decreased in the vanadium-treated animals relative to diabetic controls. Also, vanadium treatment reduced the level of hyperglycemia in diabetic rats, with sodium metavanadate being the most effective of the vanadium compounds tested. However, daily vanadium intake was significantly lower in the animals receiving sodium metavanadate. Signs of toxicity were observed in all vanadium-treated animals as evidenced by some deaths, decreased weight gain, and increased serum concentrations of urea and creatinine. Moreover, vanadium was detected in all tissues analyzed. Although some signs of diabetes were improved by vanadium treatment, because of the severe toxic side effects noted in all of the vanadium-treated animals, it seems evident that oral vanadium administration is not a suitable therapy of diabetes mellitus in streptozotocin-diabetic rats.