DNA methylation in mitochondrial NADH dehydrogenase 6 (ND6) and displacement loop (D-loop) region was significantly correlated with changes in insulin sensitivity (the event starting in an earlier stage [24–26]) but had marginal interaction with A1c and FG (the later-stage markers in prediabetes progression [24–26]). The gene discussed is MT-ND6; the disease is prediabetes syndrome.