GIP and Alzheimer disease: As receptors of GIP and GLP-1 are both discovered in Central Nervous System (CNS) (Gabe et al., 2020), and recent study shows that the same novel GLP-1/GIP receptor agonist DA4-JC shows neuroprotective effect in the different mouse model of AD (Maskery et al., 2020; Cai et al., 2021).