Epigenetic modifications in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) develops through the interplay of insulin resistance and progressive beta-cell dysfunction. Beyond genetic predisposition, epigenetic regulation provides a mechanistic link between environmental exposures (e.g., overnutrition, physical inactivity, inflammation) and durable changes in gene expression in pancreatic islets and insulin-sensitive tissues (skeletal muscle, adipose tissue, and liver). Accordingly, this review aims to synthesize current evidence on the epigenetic mechanisms underlying T2DM and its complications, with a particular focus on epigenetically targeted therapeutic strategies. We summarize major epigenetic processes, including DNA and RNA methylation, histone post-translational modifications, and non-coding RNAs, and discuss how these alterations remodel chromatin and transcriptional programs under metabolic stress. A key concept is "metabolic memory," whereby transient hyperglycemia or lipotoxicity can induce persistent epigenetic signatures that sustain dysfunctional cellular phenotypes, partly shaped by mitochondrial metabolism and Krebs cycle intermediates regulating chromatin-modifying enzymes. Importantly, several epigenetic alterations demonstrate partial reversibility following lifestyle modification, metabolic surgery, or pharmacological intervention (e.g., DNA methyltransferase inhibition), underscoring their therapeutic relevance. Finally, we address translational challenges, including limited access to human tissues and inadequate modeling of chronic metabolic stress, which currently constrain clinical exploitation of epigenetic targets in T2DM.