Furthermore, they found that the DNA methylation levels are negatively related to PGC-1α mRNA and mitochondrial DNA (mtDNA) in skeletal muscle.145 It has been acknowledged that the DNA methylation levels in the insulin promoter are elevated in patients with T2D;146 nevertheless, there are some hypomethylated CpG islands in these patients.147 In 2014, Dayeh and colleagues148 performed a genome-wide DNA methylation analysis of human pancreatic islets in patients with T2D. The gene discussed is INS; the disease is type 2 diabetes mellitus.