Procyanidin polyphenol type-A polymers extracted from cinnamon and has the ability to stimulate autophosphorylation of the insulin receptor and inhibit protein tyrosine phosphatase I. Insulin receptor kinase autophosphorylation and subsequent phosphorylation of its principal substrate are markedly decreased in insulin-responsive tissues of subjects with severe obesity or non-insulin-dependent diabetes mellitus (NIDDM) [48]. Here, INSR is linked to obesity due to melanocortin 4 receptor deficiency.