INS and type 2 diabetes mellitus: Yang et al. (2012) found out that PDX1 was one of 15 genes with CpG islands within the promoter that were methylation-susceptible in T2D (Yang et al., 2012). DNA methylation leads to reduced levels of PDX1 protein and mRNA, resulting in impaired expression of both GLUT2 and insulin and causing development of hyperglycemia (Ahlgren et al., 1998). Under high glucose concentration, DNA methylation level may increase abnormally which results in decreased insulin secretion and subsequently leads to diabetes (Pinzon-Cortes et al., 2017).