PTPN1 and type 2 diabetes mellitus: Similarly, Lu et al. [17] demonstrated that protamine Zn insulin combined with sodium selenite improved glycometabolism in T2DM via upregulating phosphatidylinositol 3-kinase (PI3K), downregulating the protein tyrosine phosphatase 1B (PTP1B: Inhibitor of the insulin receptor substrates 1 and 2 [Irs1 and Irs2]), reducing oxidative stress, and ameliorating skeletal muscle and β-cell damage, as well as mitochondrial dynamics.