Genome wide association studies (GWAS) identified a frequent single nucleotide polymorphism (SNP), rs10830963G (variation of the C allele to G), in the intronic region of the MTNR1B gene, which was associated with increased fasting plasma glucose levels and impaired insulin secretion, as well as increased risk of T2D and gestational diabetes mellitus (Bouatia-Naji et al., 2009; Lyssenko et al., 2009; Prokopenko et al., 2009). This evidence concerns the gene INS and type 2 diabetes mellitus.