INS and type 2 diabetes mellitus: Insulin administration via oral, nasal or intracerebroventricular (ICV) injections decreases AD pathology in animal models of T2DM with AD‐like changes (Adzovic et al., 2015; Avgerinos et al., 2018; Cummings et al., 2020; Freiherr et al., 2013; Morris & Burns, 2012; Steinmetz et al., 2016).