Role of vanadium in treating diabetes

Since insulin-dependent diabetes mellitus (IDDM), which causes many severe secondary complications, is characterized by hyperglyceria due to absolute deficiency of insulin, the diseases is controlled by daily injection of ins ulin. Therefore, the development of insulin replacements of mimetics upon o ral administration is an important investigation. Recent studies indicate t hat vanadium, which is proposed to be one of essential trace elements in an imals and humans, relates to both glucose and lipid metabolisms, and the me tal in turn shows insulin-mimetic effect. Thus several types of vanadium co mplex have been proposed to be insulin mimetics. In 1990, we proposed first vanadyl-cysteinate complex, which normalized the blood glucose level of ID DM rats on oral administration. On the other hand, simple vanadium compound s such as vanadyl sulfate and sodium vanadate have been reported to be usef ul to treat human non-insulin-dependent diabetes mellitus (NIDDM). Based on the observations, we have developed several types of vanadyl complexes wit h different coordination modes such as VO(O-4), VO(N-4), VO(S-4), VO(O2N2), VO(S2N2) and VO(O2S2), and found that vanadyl-methylpicolinate complex wit h long acting character and low toxicity is the most effective to treat IDD M as well as NIDDM rats, when administered orally. The mechanism was also s tudied with respect to the pharmacokinetic analysis and vanadium distributi on in animals. J. Trace Elem. Exp. Med. 12:393-401, 1999. (C) 1999 Wiley-Li ss, Inc.