MAPT and diabetes mellitus: Dysfunction of metabolism in DM may result in neurodegeneration in the brain (Patrone et al., 2014), taking the form of Aβ accumulation and tau hyperphosphorylation as the hallmarks of AD (Grundke-Iqbal et al., 1986; Selkoe and Schenk, 2003) which is accompanied by synaptic dysfunction, neurogenesis, and neuronal disorders (Michailidis et al., 2022).