On the contrary, the flavonoid myricetin up-regulated p-IR, p-IRS1 and p-AKT in the liver of HFD-fed and STZ-induced type 2 diabetic rats by inhibiting the activity and expression of PTP1B, the tyrosine phosphatase that negatively regulates the insulin signal transduction [38]. This evidence concerns the gene IRS1 and type 2 diabetes mellitus.