The AGE-RAGE-DIAPH1 Axis in Type 2 Diabetes and Metabolic Dysfunction: From Carbonyl Stress to Diabetic Myocardial...

Carbonyl stress, chronic inflammation, and progressive tissue injury accompany type 2 diabetes mellitus (T2DM) and obesity. Yet, the molecular systems that connect these processes with cardiac, vascular and neuronal complications are incompletely defined. This review examines the AGE-RAGE-DIAPH1 axis as a mechanistic link between metabolic dysfunction and diabetic myocardial and neuronal injury, with emphasis on vascular and myocardial remodeling and emerging implications for autonomic neuronal vulnerability. We summarize current evidence on the formation and accumulation of advanced glycation end-products and other RAGE ligands in metabolic disease, DIAPH1's structural and signaling role as an intracellular effector of RAGE, and the cellular consequences of pathway activation in vascular, neural, and cardiac tissues. Across experimental models, this signaling axis promotes oxidative stress and inflammatory activation, leading to endothelial dysfunction and barrier failure. Subsequent fibrotic remodeling provides a biologically plausible route through which metabolic stress may be translated into persistent organ injury. In the heart, these mechanisms are linked to coronary microvascular dysfunction, altered cardiomyocyte phenotype, calcium handling abnormalities, and myocardial fibrosis. In the autonomic nervous system, limited but emerging data connect RAGE activation to oxidative injury and mitochondrial dysfunction, abnormal neuronal excitability, and structural vulnerability. Direct evidence linking DIAPH1 to autonomic neurons is lacking. We also review biomarker candidates related to this pathway, including circulating AGEs and soluble RAGE isoforms, skin AGE measurements, imaging markers of myocardial remodeling, and autonomic functional measures. Finally, we discuss pharmacological and natural compounds that target AGE formation, ligand accumulation, RAGE signaling, or intracellular protein interactions linked to this axis. Overall, the available evidence supports the AGE-RAGE-DIAPH1 axis as a credible mechanistic concept and a potentially informative translational hypothesis in T2DM. However, the AGE-RAGE component is supported more strongly than DIAPH1-specific involvement in human diabetic myocardial disorder or cardiovascular autonomic neuropathy. The value of DIAPH1 as a biomarker or therapeutic target in these neurocardiac complications remains to be established.