OBJECTIVES: To describe patterns of cognitive deficits and activities of daily living (ADLs) in older people with diabetes mellitus. DESIGN: Cross-sectional, population-based study. SETTING: Three homecare agency areas in Boston, Massachusetts. PARTICIPANTS: Two hundred ninety-one homebound people aged 60 and older; 40% with diabetes mellitus. MEASUREMENTS: Demographic data; evidence of diabetes mellitus and other diseases; Mini-Mental State Examination and tests of memory and executive function; ADLs. RESULTS: Executive and visuospatial functions were more impaired in individuals with diabetes mellitus than in those without, as assessed using Block Design (mean score±standard deviation 17.1±8.6 vs 20.5±9.6, P = .003) and Trails B (median seconds to accomplish the task: 255 vs 201, P = .03). For memory, word retention score was lower in those with diabetes mellitus than without (39.1±28.9 vs 48.0±29.7, P = .01), but the other memory tests did not show a difference between these two subgroups. More individuals with diabetes mellitus suffered from depressive symptoms than those without (55% vs 42%, P = .03). The ADL scores of those with diabetes mellitus were higher than those without. CONCLUSION: The pattern of cognitive deficits in people with diabetes mellitus suggests frontal-subcortical dysfunction, as seen in microvascular disease of the brain. The impairment in ADLs may be associated with this executive dysfunction, which cerebral microvascular disease in diabetes mellitus may cause.