T2DM patients with genotype CC at MTNR1B rs10830963 had a significant decrease in FPG (mmol/L) when compared with the genotypes CG and GG (− 3.75 ± 1.68 vs − 2.87 ± 1.32; P < 0.05) respectively. This evidence concerns the gene MTNR1B and type 2 diabetes mellitus.