INS and Alzheimer disease: It is particularly noteworthy that the reductions in GLP-1 and GIP-1 could exacerbate the deficiencies in brain insulin levels and worsen impairments in brain insulin signaling, since both GLP-1 and GIP-1 are incretins with insulinotropic functions, and they are important regulators of glucose metabolism [73] that could be used therapeutically to treat cognitive impairment and neurodegeneration in AD [18,74].