Association of diabetes, comorbidities, and A1C with functional disability in older adults: Results from the National Health and Nutrition Examination Survey (NHANES), 1999-2006

OBJECTIVE - To examine the relationship of diabetes and functional disability in older adults and the possible mediating roles of comorbidities and A1C. RESEARCH DESIGN AND METHODS - We analyzed data from a nationally representative sample of 6,097 participants aged ≥60 years in the National Health and Nutrition Examination Survey, 1999-2006. Diabetes was defined by self-report. Disability was defined as difficulty performing a physical task. We evaluated disability by grouping 19 physical tasks into five functional groups: lower-extremity mobility (LEM), general physical activities (GPA), activities of daily living (ADL), instrumental activities of daily living (IADL), and leisure and social activities (LSA). RESULTS - Older U.S. adults with diabetes had the greatest disability in GPA (prevalence 73.6% [95% CI 70.2-76.9]), followed by LEM (52.2% [48.5-55.9]), IADL (43.6% [40.1-47.2]), ADL (37.2% [33.1-41.3]), and LSA groups (33.8% [30.8-36.9]). Diabetes was associated with two to three times increased odds of disability across functional groups (all P < 0.05). Comorbidities, mostly cardiovascular disease and obesity, and poor glycemic control (A1C ≥8%) together explained up to 85% of the excess odds of disability associated with diabetes, whereas poor glycemic control alone explained only ∼10% of the excess odds. Adjustment for comorbidities, A1C, and diabetes duration fully attenuated the associations of diabetes with disability in all functional groups (all P > 0.05). CONCLUSIONS - Older adults with diabetes have a high prevalence of disabilities with variable associations attributable to comorbidities and A1C. Aggressive management of cardiovascular risk factors and obesity may significantly reduce the burden of disability in this population.