Connecting the Dots: Neurobiological Interplay Between Type 2 Diabetes and Alzheimer's Disease

Diabetes Mellitus is a chronic metabolic disorder characterized by impaired insulin production and/or action, leading to persistent hyperglycemia and insulin resistance. It has been associated with several comorbidities, including cognitive dysfunction, affecting functions such as attention, memory, and processing speed. Mounting evidence indicates a complex relationship between type 2 Diabetes Mellitus (DM2) and neurodegenerative disorders such as mild cognitive impairment and Alzheimer's disease (AD). Beyond the conventional hallmarks of each pathology, patients with DM2 face an increased risk of neuronal degeneration, while AD is characterized by a marked reduction in insulin receptor density. Although aging, neuroinflammation, and vascular dysfunction have been recognized as key risk factors in AD, the precise molecular mechanisms driving AD pathogenesis remain incompletely understood. Various studies have been conducted to identify reliable biomarkers that elucidate the connection between DM2 and AD, including insulin dysregulation, neuroinflammation, amyloid-β aggregation, and tau hyperphosphorylation. Investigation of these biomarkers is still ongoing, and they may serve not only as diagnostic tools but also as therapeutic targets. Here, we review the current evidence supporting a convergent biological framework between DM2 and AD. Clarifying these shared pathways may improve early detection and guide the development of targeted therapeutic strategies aimed at reducing neurodegeneration in metabolically vulnerable populations.