IRS1 and hyperinsulinism: First, consistent with the ambient postprandial hyperinsulinemia present in MetS mice 1 h after oil gavage, the intestines of these mice, as compared with controls, had much higher levels of phosphorylated AKT (Fig 6B), higher mRNA content of the insulin receptor (IR) and insulin receptor substrate 1 (IRS1) (Fig 6C).