To achieve this objective, studies about the pathophysiological mechanisms of neurodegenerative processes and their relationship with IR and T2DM will be reviewed, sourced from Pubmed, Scopus, Science Direct and other relevant databases, using the following keywords: neurodegenerative diseases, cognitive impairment, dementia, Alzheimer’s disease, beta-amyloid, Tau, insulin resistance, insulin, type 2 diabetes mellitus, prevention and treatment of neurodegenerative diseases. The gene discussed is INS; the disease is early-onset autosomal dominant Alzheimer disease.