Naglivan [PMD 501, vanadeine] is a vanadyl organometallic agent, in the preclinical phase of development in France, with Pan Medica, as an orally-active drug for the treatment of diabetes mellitus. Naglivan is an orally effective form of vanadyl with an oral potency 7.6 times greater than that of vanadyl sulfate (minimum effective dose: 0.06 mmol vanadium.kg-1.day-1) as compared to vanadyl sulfate (0.46 mmol vanadium.kg-1.day-1). The lack of incidence of diarrhea in either control or diabetic animals demonstrates that naglivan could be a more therapeutically desirable form of vanadyl.