IRS1 and diabetes mellitus: In HFD-induced mice treated with 400 mg/kg of 0.5% baicalein, a study showed that the activation of AMPK can downregulate insulin receptor substrate 1 (IRS-1) and Akt through phosphorylation and can also reduce SREBP-1c and FAS gene transcription and upregulate PPAR-α gene expression and fat target genes to inhibit cholesterol and fatty acid synthesis, thereby further achieving the purpose of treating DM (Pu et al., 2012).