Some large population studies support an association between type 2 diabetes caused by insulin resistance and dementia [2–4]; although these studies were not able to establish the association between insulin resistance and dementia, because of the neurotoxic effects of hyperglycemia, a key feature of type 2 diabetes, a study with intranasal insulin administration reported improved memory and other cognitive functions in type 2 diabetes and suggested the association between insulin resistance and dementia [5, 6]. This evidence concerns the gene INS and type 2 diabetes mellitus.