Abstract
This manuscript provides a brief review of the epidemiologic evidence linking type 2 diabetes (T2D) and its precursor conditions, elevated adiposity and hyperinsulinemia, to dementia. Elevated adiposity in middle age is related to a higher risk of dementia but the data on this association in old age is conflicting. Hyperinsulinemia, a consequence of higher adiposity and insulin resistance is also related to a higher risk of dementia, including late onset Alzheimer's disease (LOAD). Studies have consistently shown a relation of T2D with higher dementia risk, but the associations are stronger for vascular dementia compared to LOAD. One implication of these associations is that strategies used to prevent T2D can be used to prevent dementia. Several studies in the prevention and treatment of T2D are currently measuring cognitive outcomes and will provide information on whether T2D treatment and prevention can prevent cognitive decline and dementia.