INS and diabetes mellitus: The mechanism of cognitive dysfunction in patients with diabetes mellitus has been suggested to be related to: (1) insulin resistance in the local brain [7,33]; (2) chronic inflammation, deposition of advanced glycation end-products (AGEs), and mitochondrial dysfunction; (3) τ (tau) deposition; (4) low adiponectin level in blood [34]; and (5) hypoglycemia due to exogenous and endogenous insulin [35,36].