IRS1 and type 2 diabetes mellitus: Regarding type 2 diabetes, the response to drugs that stimulate insulin secretion by pancreatic cells or to increase insulin sensitivity is influenced by the polymorphism of the IRS1 Gly972Arg receptor (widespread in some populations, e.g., Italian and French) which contributes to the failure of some specific therapies by altering the link between the IRS1 substrate and other molecules that mediate the final effect of insulin [33].