D-chiro-inositol--its functional role in insulin action and its deficit in insulin resistance

In this review we discuss the biological significance of D-chiro-inositol, originally discovered as a component of a putative mediator of intracellular Insulin action, where as a putative mediator, it accelerates the dephosphorylation of glycogen synthase and pyruvate dehydrogenase, rate limiting Enzymes of non-oxidative and oxidative glucose disposal. Early studies demonstrated a linear relationship between its decreased urinary excretion and the degree of Insulin resistance present. When tissue contents, including muscle, of type 2 diabetic subjects were assayed, they demonstrated a more general body deficiency. Administration of D-chiro-inositol to diabetic rats, Rhesus monkeys and now to humans accelerated glucose disposal and sensitized Insulin action. A defect in vivo in the epimerization of myo-inositol to chiro-inositol in Insulin sensitive tissues of the GK type 2 diabetic rat has been elucidated. Thus, administered D-chiro-inositol may act to bypass a defective normal epimerization of myo-inositol to D-chiro-inositol associated with Insulin resistance and act to at least partially restore Insulin sensitivity and glucose disposal.