Background: Type 2 diabetes mellitus requires long-term outpatient management. Medication adherence is important for treatment effectiveness, but self-reported measures may be affected by recall bias, social desirability bias, and ceiling effects.
Objective: To describe self-reported medication-adherence scores and explore factors associated with the maximum self-reported E1–E7 score among outpatients with type 2 diabetes.
Methods: A cross-sectional analytical study was conducted among 178 outpatients with type 2 diabetes recruited by convenience sampling at Tam Nong Regional Health Center, Dong Thap Province, in 2026. Medication-taking behavior was assessed using the 7-item self-reported E1–E7 questionnaire developed by the research team with reference to the Medication Compliance Questionnaire; it was not a translated and validated Vietnamese version of the MCQ. Scores ranged from 7 to 28. Scores ≥27 and 28/28 were treated as descriptive questionnaire thresholds, not validated clinical adherence categories.
Results: The mean age was 59.8 ± 10.7 years; women accounted for 71.9%. The mean E1–E7 score was 27.49 ± 1.15, and the median was 28 (IQR, 27–28). Overall, 92.1% scored ≥27 and 71.3% scored 28/28, indicating a marked ceiling effect. In a limited exploratory logistic model, age and family history of diabetes were associated with the maximum self-reported score; these estimates were not adjusted for several clinical confounders and have no predictive interpretation.
Conclusion: E1–E7 questionnaire scores were concentrated at the upper limit, with a marked ceiling effect and limited discrimination. Findings should be interpreted as preliminary descriptive and exploratory evidence.