MTNR1B and type 2 diabetes mellitus: To investigate potential correlations between MTNR1B genetic variants and T2DM, eight studies about rs1387153 variant (12,799 cases and 11,382 controls), two studies about rs4753426 variant (526 cases and 1,301 controls), two studies about rs10830962 variant (763 cases and 811 controls), and eighteen studies about rs10830963 variant (30,259 cases and 39,561 controls) were enrolled to analyses.