Although most of GDM genetic studies have been preferentially conducted for candidate genes, meta-analyses have consistently revealed variants near previously T2D associated genes, i.e. TCF7L2, MTNR1B, IGF2BP2, KCNJ11, CDKAL1, KCNQ1, GCK and IRS1 [63, 64]. This evidence concerns the gene GCK and type 2 diabetes mellitus.