INS and type 2 diabetes mellitus: While emerging evidence suggest that dysregulation of neuronal insulin signaling, so-called cerebral insulin resistance, may play central role in cognitive dysfunction (de la Monte, 2012; Ferreira et al., 2014; De Felice and Benedict, 2015; Grillo et al., 2015; Nuzzo et al., 2015), the exact mechanisms by which T2DM influences the cognitive function and dementia risk are yet to be elucidated.