The prevalence of self-reported diabetes in U.S. adults aged ≥60 years was 16.2% (95% CI 15.2–17.2%), with no significant secular trends across survey periods. Diabetes was significantly more common in non-Hispanic blacks and Mexican Americans, individuals with higher BMI or waist circumference and lower attained education level, and nonsmokers (). The mean A1C of older adults with diabetes was 7.1%. Most took oral medications alone, although 26.2% took insulin, including 10.8% taking combined therapy. The mean diabetes duration was 13.8 years.
Nationally representative demographic and clinical characteristics of older U.S. adults with and without diabetes, NHANES, 1999–2006
Older adults with diabetes had a greater burden of comorbidities than adults without diabetes. This included a significantly higher prevalence of CHD, CHF, stroke, hypertension, hypercholesterolemia, neuropathy, PAD, leg ulcers or amputations, visual or hearing impairment, memory problems, obesity, and arthritis. CKD prevalence was slightly higher in the diabetic group but was not statistically significant compared with that for the nondiabetic group.
Older adults with diabetes were more likely to report difficulty performing tasks in each functional group compared with older adults without diabetes; we did not find significant secular trends or evidence for effect modification by sex, race/ethnicity, or age-group. Thus, overall results are presented (supplementary Fig. 1, available in an online appendix at http://care.diabetesjournals.org/cgi/content/full/dc09-1597/DC1
). Among older adults with diabetes, the greatest difficulty was 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 significantly associated with having difficulty in at least one functional group after adjustment for demographic factors (adjusted OR 1.94 [1.57–2.40]; prevalence 76.9% [73.4–80.3]).
When taken together, comorbidities and suboptimally controlled glucose (A1C ≥8%) were associated with 59% (ADL), 72% (IADL), 79% (GPA), and 85% (LEM and LSA) of the excess odds of disability observed in older adults with diabetes. Cardiovascular disease (including CHD, CHF, and stroke) and obesity together were associated with 37% (ADL), 40% (IADL), 53% (GPA and LEM), and 46% (LSA) of the excess odds of disability linked with diabetes across functional groups. Suboptimally controlled glucose alone was associated with 0% (IADL), 5% (LEM and ADL), 9% (LSA), and 10% (GPA) of the excess odds of disability.
In logistic regression models, diabetes was associated with significantly higher odds of disability across all functional groups after adjustment for demographic factors (adjusted ORs ranged from 1.97 to 2.53, all P < 0.05) (, model 1). Adjustment for A1C and diabetes duration moderately attenuated these associations, but they remained statistically significant across all groups (, models 2 and 3). However, further adjustment for cardiovascular disease and obesity largely attenuated the ORs (, model 4), resulting in nonsignificant associations between diabetes and disability in all functional groups. An overall F-adjusted test statistic of 0.70 (P = 0.71) represented good model fit.
Nationally representative ORs for the association of diabetes and disability among older U.S. adults after adjustment for A1C, diabetes duration, and diabetes-related comorbidities, NHANES, 1999–2004
ORs for the association of other covariates including demographics, A1C, diabetes duration, and comorbidities with disability in fully adjusted models (as described in , model 5) across functional groups are provided in supplementary Table 1 (available in an online appendix). Among older adults, the ORs for diabetes are weaker than those for comorbidities such as hip fracture, arthritis, and memory problems, which all have adjusted ORs >2. However, because the ORs for these conditions (in particular memory problems) were self-reported, they may not be as reliable. In addition, visual impairment, hearing difficulties, and COPD were associated with significantly greater disability across all groups (adjusted ORs ranged between 1.46 and 2.44; all P < 0.05). In contrast, the ORs for CHD and stroke were weaker and nonsignificant (P > 0.05) for most but not all groups.
In sensitivity analyses, when disability was defined as inability to perform a task, we found that diabetes remained significantly associated with disability across functional groups as follows: LEM (demographics adjusted OR 2.91 [95% CI 2.39–3.54]), GPA (2.64 [2.14–3.27]), ADL (3.93 [2.39–6.47]), IADL (2.58 [1.87–3.56]), and LSA (3.67 [2.54–5.31]). Diabetes was also associated with an increased odds of having a history of falls, dizziness, or balance problems (adjusted OR 1.75 [95% CI 1.40–2.19]; prevalence 40.3% [35.6–44.9]), needing special assistance or an assistive device (adjusted OR 2.60 [2.02–3.35]; prevalence 22.7% [18.9–26.5]), or having a disability that prevented the participant from working (adjusted OR 2.12 [1.80–2.51]; prevalence 27.1% [23.7–30.5]) after adjustment for demographic factors. Among older adults with diabetes, we found that neither glycemic control, insulin use, nor duration of diabetes was significantly associated with disability in any functional group after adjustment for demographics and comorbidities (all P > 0.05).