MTNR1B and type 2 diabetes mellitus: T2D risk variants at the MTNR1B, FTO, TLE1, G6PC2, GCKR, TCF7L2, ADCY5, CDKAL1, TCF2, HNF1B, PPARG, KCNJ11, SLC30A8 loci have previously been associated with GDM in European populations [15–18] whereas variants in the CDKAL1, CDKN2A/2B, MTNR1B and KCNQ1 loci were associated with GDM in Korean women [19, 20].