IRS1 and type 2 diabetes mellitus: Moreover, a number of candidate genes previously linked through GWAS to T2DM and obesity were found to be differentially expressed in the adipose tissue from discordant twins, including PPARG, GLIS family zinc finger 3 (GLIS3) (T2DM), vascular endothelial growth factor A (VEGFA), and IRS1 (obesity) [107].