Functional status and health outcomes in older Americans with diabetes mellitus

OBJECTIVES: To determine how baseline functional status affects health outcomes in older adults with diabetes mellitus (DM). DESIGN: Nationally representative cross-sectional and longitudinal health interview survey. SETTING: Waves I (1993) and II (1995) of the Assets and Health Dynamics of the Oldest Old Survey (AHEAD) in the United States. PARTICIPANTS: AHEAD respondents aged 70 and older (n = 7,447, including 995 with DM). MEASUREMENTS: At baseline, the entire sample was divided into three groups: high-functioning group, defined as having no physical limitations or instrumental activities of daily living/activities of daily living (IADL/ADL) disabilities (39%); low-functioning group, having three or more limitations or IADL/ADL disabilities (24%); and intermediate-functioning group, those in the middle (36%). Older adults with and without DM, within each of the functioning groups, were compared at 2-year follow-up with respect to demographic characteristics, weight/body mass index, baseline and incident chronic diseases and conditions, and follow-up functioning. RESULTS: Of people aged 70 and older, 28% with DM and 41% without were high functioning; 38% with DM and 22% without were low functioning (both P < .001). High-functioning people with DM remained high functioning at 2 years but had a significantly higher incidence of heart disease and mortality than high-functioning people without DM. Low-functioning people with DM were significantly more likely to have vascular comorbidities at baseline than low-functioning people without DM, but their 2-year outcomes were similar. The intermediate-functioning group showed the most differences between those with and without DM; those with DM were significantly (P < .01) more likely to have baseline vascular disease, low cognitive performance, increased incident vascular disease, and significantly worse 2-year functioning and to have experienced falls (P < .001). CONCLUSION: Differences in baseline functional status in older adults with DM were associated with outcome differences. High-functioning older people with DM tended to remain high functioning but demonstrated significantly higher incidence of heart disease and mortality than those without DM, whereas low-functioning people with and without DM had similar outcomes. However, intermediate-functioning older diabetics had worse health and functioning outcomes than a similarly impaired group without DM. DM management adjusted to functional status can potentially address the most-relevant outcomes in the heterogeneous older population with DM.