The core biomarker for the specific diagnosis of AD, the 42 amino acid Aβ isoform Aβ42, is associated with IR, promotes plaque formation, and plays a key role in the pathogenesis of AD (Teunissen et al., 2018), and it has been demonstrated that levels of cerebrospinal fluid (CSF) Aβ42 increased during the very early phase of cerebral Aβ deposition in mouse models (Maia et al., 2015), whereas the reduced insulin sensitivity impairs the role of insulin in inhibition of Aβ42 aggregation and Aβ42‐induced neuron damaged prevention (Long et al., 2019). The gene discussed is INS; the disease is Alzheimer disease.