IRS2 and Hyperglycemia: In addition, exposure of mouse pups to a high-fat diet in the fetal period leads to hyperglycemia, high serum leptin, and methylation modification disorder of the hepatic insulin receptor substrate 2 (Irs2) gene, the mitogen-activated protein kinase kinase 4 (Map2k4) gene, the hypothalamic proopiomelanocortin (Pomc) gene, and the melanocortin 4 receptor (Mc4r) gene (32, 33).