IRS1 and Insulin resistance: A TCM formula called “wumei wan” in Chinese has also been reported to improve insulin resistance (IR) in type 2 DM rats, which might be related to up-regulation of protein and mRNA expression levels of the insulin receptor (Insr), insulin receptor substrate 1 (Irs-1), glucose transporter4 (Glut-4), and β-arrestin-2 in the liver and skeletal muscle (Li et al., 2013).