Subsequent replication studies in large-scale case–control and cohort research provided robust evidence that the glucose-elevating allele (MTNR1B rs10830963) was associated with glycemic traits such as impaired glucose tolerance, inhibited β-cell function, increased fasting glucose levels and T2DM in Europeans [30,112–114], Asians [115–118], North Americans [119] and African Americans, among others [120,121]. Here, MTNR1B is linked to Impaired glucose tolerance.