The single nucleotide polymorphisms (SNPs) in some of these genes have only a small effect on the disease status, but few, like those at the transcription factor 7-like 2 gene (TCF7L2) and proliferator-activated receptors-γ2 (PPAR-γ2) have a profound effect on the T2DM prevalence, as has previously been reported in large scale studies or meta-analyses conducted in various populations and ethnic groups [9–11]. This evidence concerns the gene TCF7L2 and type 2 diabetes mellitus.