IRS1 and type 2 diabetes mellitus: For type II diabetes patients, the insulin signal transmission pathway through insulin receptors (IRS1, IRS2) and phosphatidylinositol 3-kinase (PI3K) (PI3K) is damaged, which results in the decrease in glucose absorption stimulated by insulin in skeletal muscle, while the noninsulin signal transmission pathway of AMPK in these patients is normal.