As the population getting older, the chronic diseases will be more prevalent as diabetes mellitus (DM) and diseases characterized by cognitive deficits, as dementia. Studies have already shown an association between DM and cardiovascular risk factors associated with cognitive impairment. Besides the vascular complications of DM, studies have proposed the role of hyperglycemia and advanced glycosilation end products (AGEP) causing oxidative stress and beta-amyloid protein brain deposition. Other factors have also been investigated, such as the role of insulinemia, genetic and IGF-1 (insulin-like growth factor-1). Some studies showed that good glucose control and intake of polyunsaturated fat, Omega-3 or anti-oxidative food can play a protector role against cognitive deficits. Improving knowledge about the association between DM and cognition and its physiopathology, can be essential for the prevention and treatment of cognitive impairment, leading to a beneficial impact on the quality of life of elderly patients with DM.