INS and Alzheimer disease: Based on the link between AD and T2DM, it is reasonable to think that insulin enhancement agents could have the capacity to prevent AD progression and drugs for T2DM treatment such as the peroxisome proliferator-activated receptor γ (PPARγ) agonists are potential candidates for the treatment of AD (Landreth et al., 2008; Nicolakakis and Hamel, 2010).