Diabetes and cognitive systems in older black and white persons.

We examined the association of type 2 diabetes mellitus to function in different cognitive systems in older black and white persons. Participants were 1437 persons (28.1% black; 72.9% women; mean age 78.4 y, education 14.5, Mini-Mental State Examination 27.9) free of dementia, enrolled in the Minority Aging Research Study or Memory and Aging Project, 2 epidemiologic, community-based cohort studies of aging and cognition. Summary measures of 5 cognitive domains and global cognition were derived from 19 neuropsychologic tests. Diabetes, by medication inspection and history, was present in 15.3% participants, including 23.5% blacks and 12.1% whites (P<0.001). In linear regression models adjusted for age, sex, education, and race, diabetes was associated with a lower level of semantic memory (P=0.042), but not other cognitive domains (episodic memory, working memory, perceptual speed, and visuospatial ability) or global cognition. In separate analyses adjusted for age, sex, education, race, and diabetes, there was no interaction of diabetes with race (all P values >0.333). In summary, diabetes was associated with semantic memory impairment in both black and white persons. We found similar effects of diabetes on cognition in both racial groups. Because diabetes is twice as common in blacks, the burden of diabetes on cognition is higher in black than white persons.