IRS2 and type 2 diabetes mellitus: Until now, about 3644 single nucleotide polymorphisms (SNP) in the IRS1 gene and 1704 SNP in the IRS2 gene have been reported (http://www.ncbi.nlm.nih.gov/SNP), some of which have been shown as susceptible loci for several kinds of diseases, such as cancer and Type 2 diabetes mellitus (T2DM) [15]–[19].