MTNR1B and type 2 diabetes mellitus: In the present study, we aimed to verify the associations of 19 single nucleotide polymorphisms (SNPs) in 11 genes (PPARG, IGF2BP2, CDKAL1, SLC30A8, CDKN2A/2B, HHEX, EXT2, KCNJ11, KCNQ1, MTNR1B and TCF2) with the risk of T2DM and IGR in Chinese population; and followed by the investigation of the combined effect of these genes on the risk of T2DM in both case-control study and prospective cohort.