Association of health literacy with self-management behavior in patients with diabetes.

L imited health literacy, common in patients with diabetes, has been associated with worse diabetes outcomes (1–4). While patients with limited health literacy have worse diabetes knowledge (2–5), knowledge does not necessarily predict outcomes (6–8). Because diabetes requires extensive selfcare, differences in self-management behaviors may be a key contributor to the disparity in outcomes. In fact, low health literacy has been associated with poor self-care in other chronic illnesses (9,10). However, no study has examined the relationship between health literacy and self-management behaviors in patients with diabetes. In addition, studies have not assessed whether diabetes education, which is widely recommended, is effective in improving selfmanagement behaviors in patients with limited health literacy. The objectives of our study were to examine the associat ion of health literacy with selfmanagement behaviors in patients with diabetes and to determine whether diabetes education improves self-management behaviors in patients with limited compared with adequate health literacy. Understanding the relationship between health literacy and self-management behaviors should enhance efforts to improve diabetes outcomes. RESEARCH DESIGN AND METHODS — We conducted a prospective observational study of patients enrolled in diabetes education classes at the Hospital of the University of Pennsylvania. The classes consist of an individual meeting with a diabetes educator and three weekly 3-h group classes and are recognized by the American Diabetes Association (11). All patients 18 years of age present for a regularly scheduled diabetes class were recruited. Patients who did not speak English were excluded. Participants were compensated with a $10 gift certificate. Written consent was obtained, and the institutional review board approved this study. At the first class, diabetes educators administered a questionnaire regarding demographic information, social support (12), and diabetes history. Health literacy was measured with the short-form Test of Functional Health Literacy in Adults, a 36-item timed reading comprehension test shown to be a valid measure of functional health literacy (13). Patients scoring 22 on the 36-point scale were considered to have inadequate or marginal health literacy. Self-management behaviors were assessed using the Summary of Diabetes Self-Care Activities Measure (SDSCA), a valid self-report measure that assesses how often self-care activities (diet, exercise, self-glucose monitoring, foot care, and medication adherence) are performed in a given week (14). Other outcome measures included knowledge, using the Diabetes Knowledge Questionnaire (DKQ) (15), and glycemic control, which was assessed by obtaining HbA1c levels from medical records. Follow-up questionnaires (DKQ, SDSCA) were administered by telephone interview. Baseline differences in demographics and DKQ and SDSCA scores between literacy groups were compared with t tests and 2 tests. The DKQ and SDSCA baseline and 3-month values within literacy groups were compared with paired t tests. Nonparametric tests were also performed; there were no differences in results. Effect sizes, which summarize the magnitude of differences between and within groups relative to the pooled SD, were computed. Effect sizes are standardly interpreted as 0.20 small effect, 0.50 moderate effect, and 0.80 large effect. ANCOVA compared 3-month outcomes adjusting for baseline values, age, years of education, and income. A second ANCOVA omitted education as a covariate; the results were nearly identical.