IRS1 and Insulin resistance: The mechanism by which leptin acts on insulin resistance involves the inhibition of gluconeogenesis through modulation of the autophosphorylation of IRTK, the tyrosine phosphorylation of PI3K, and the interaction between IRS-1 and growth factor receptor-binding protein 2 (GRB2), thereby impeding insulin signal transduction and attenuating its effects [1].