TCF7L2 and gestational diabetes: Genome-wide association studies and candidate gene studies had already identified several genes that associated with risk of T2DM, and some of them were also verified to be associated with GDM risk by candidate gene studies and one GWA study including TCF7L2, GCK, KCNJ11, KCNQ1, CDKAL1, IGF2BP2, and IRS1 genes [6].