Insulin is a hormone released primarily by the pancreas. It can cross the blood-brain barrier (BBB) to have CNS effects. However, if one develops insulin resistance, which is correlated with AD, normal tissues fail to sufficiently respond to the presence of insulin. In these cases, insulin dysregulation induces hyperglycemia, too much sugar in the blood, which leads to glucose neurotoxicity, reduced cerebral blood flow, and accumulation of toxic byproducts in the brain, all of which can lead to cognitive impairment.