Design of vanadium compounds as insulin enhancing agents

Vanadium compounds, in vitro, stimulate glucose uptake and inhibit lipid breakdown, in a manner remarkably reminiscent of insulin's effects. In vivo, vanadium enhances insulin's plasma glucose and lipid-lowering properties, leading to normalization of diabetic symptoms in the presence of only minimal endogenous insulin. The coordination chemistry of vanadium has great versatility for adjustment of pharmacological characteristics. Vanadium compounds are generally also very redox active, which is both advantageous and detrimental for optimizing biochemical function. In this perspective, we review and comment on how these properties have been revealed, what questions have arisen along the way, and where future investigations may be headed. While this is not a comprehensive overview of all available compounds touted as 'insulin enhancing agents', it will focus on those which are distinctive in some way, or which are representative of the larger library of vanadium compounds, including all currently known relevant oxidation states of vanadium.