GLP1R and diabetes mellitus: Increasing evidence suggests that anti-diabetes medicine, GLP-1R agonists, have multiple neuroprotective mechanisms in AD models, such as anti-inflammation, anti-oxidative stress, reducing Aβ aggregation/deposition and tau protein hyperphosphorylation, reducing neuronal apoptosis and neurotoxicity, increasing cell proliferation and neurogenesis, increasing synaptic plasticity, and other beneficial effects.