Regarding vanadium toxicity, it has been shown that it is dramatically reduced when oligomerized in the form of decavanadate [20-23].

Then, four drops of concentrated hydrochloric acid (37%) at room temperature were added to allow decavanadate anion formation at pH 6.

Metformin decavanadate has shown hypoglycemic and hypolipidemic effects on models of type 1 and type 2 diabetes mellitus.

Isopolyanions (e.g., decavanadate) may be a good candidate.

Preparation of Decavanadate. The decavanadate ([K.sub.6][V.sub.10][O.sub.28] x 9[H.sub.2]O) was prepared according to a described procedure [41].

McLauchlan et al., "Inhibitory effects of decavanadate on several enzymes and Leishmania tarentolae in vitro," Journal of Inorganic Biochemistry, vol.