Health Literacy and Health-Related Quality of Life in Older Adults with Type 2 Diabetes: The Mediating Role of Treatment Regimen Adherence

Background and objective: It is unclear how health literacy is associated with health-related quality of life. The aim of this study was to examine the mediating role of treatment regimen adherence between health literacy and health-related quality of life (HRQoL) in older adults with type 2 diabetes mellitus (T2DM). Material and methods: In this cross-sectional study, a multi-stage cluster sampling method was used to recruit 300 diabetic patients aged 60 years and over with diabetes. The abbreviated version of the Test of Functional Health Literacy in Adults (S-TOFHLA) and the Swedish Health-related Quality of Life (SWED-QUAL) instrument were used to measure health literacy and HRQoL, respectively. In addition, the Morisky Medication Adherence Scale (MMAS), the diet and exercise adherence questionnaire, were used to assess treatment regimen adherence. The four steps of Baron and Kenny’s procedure were implemented to test the mediation hypotheses. Results: The mean age of the respondents was 64.92 years. In addition, the mean of the respondents’ health literacy score was 52.82. The prevalence rates of the inadequate, marginal, and adequate health literacy of the respondents were 70%, 14.7%, and 15.3%, respectively. Two items of treatment regimen adherence (medication adherence and diet and exercise adherence) had a partial mediating role between health literacy and quality of life in elderly diabetes patients. The result of Baron and Kenny’s procedure and Sobel’s test showed a significant mediation role in medication adherence (p = 0.00, Sobel’s Z = 2.77) and diet and exercise adherence (p = 0.00, Sobel’s Z = 6.26) between health literacy and HRQoL. Conclusion: Medication adherence, diet adherence, and exercise adherence are mediating factors in relationship between health literacy and HRQoL that increase the health literacy and quality of life in older adults with T2DM.