Type 2 Diabetes and Alzheimer’s Disease: Molecular Mechanisms and Therapeutic Insights with a Focus on Anthocyanin

Type 2 Diabetes Mellitus (T2DM) is a recognized risk factor for Alzheimer’s Disease (AD), as epidemiological research indicates that those with T2DM have a markedly increased risk of experiencing cognitive decline and dementia. Chronic hyperglycemia and insulin resistance in T2DM hinder cerebral glucose metabolism, reducing the primary energy source for neurons and compromising synaptic function. Insulin resistance impairs signaling pathways crucial for neuronal survival and plasticity, while high insulin levels compete with amyloid-β (Aβ) for breakdown by insulin-degrading enzyme, promoting Aβ buildup. Additionally, vascular issues linked to T2DM impair blood–brain barrier functionality, decrease cerebral blood flow, and worsen neuroinflammation. Elevated oxidative stress and advanced glycation end-products (AGEs) in diabetes exacerbate tau hyperphosphorylation and mitochondrial dysfunction, worsening neurodegeneration. Collectively, these processes create a robust biological connection between T2DM and AD, emphasizing the significance of metabolic regulation as a possible treatment approach for preventing or reducing cognitive decline. Here, we review the relationship between T2DM and AD and discuss the roles insulin, hyperglycemia, and inflammation therapeutic strategies have in successful development of AD therapies. Additionally evaluated are recent therapeutic advances, especially involving the polyflavonoid anthocyanin, against T2DM-mediated AD pathology.