IRS1 and type 2 diabetes mellitus: Immunohistochemical analysis of skeletal muscle and liver in SDM rats (15 days) and T2DM rats (4 months) showed that SDM rats had higher glycogen levels in the liver and skeletal muscle than CTL and T2DM rats (Fig. 4a).GLUT4, IRS-1, and PI3Kp85α were higher in the skeletal muscle of SDM rats than that of CTL and T2DM rats; there was no significant difference in the expression of GLUT4, IRS-1, and PI3Kp85α in skeletal muscle between T2DM and CTL rats (Fig. 4b).