Brain insulin resistance in type 2 diabetes and Alzheimer disease: concepts and conundrums

Alzheimer disease (AD) and related dementias share numerous mechanistic and epidemiological similarities with type 2 diabetes mellitus (T2DM). However, whether these associations result from synergistic interactions between the disorders is unclear. This Review summarizes our current knowledge regarding insulin signalling and resistance in the brain and discusses current evidence concerning neurological impairment in T2DM and insulin resistance in AD.