Development and psychometric validation of a medication literacy scale for glucose-lowering therapy in Chinese adults with type 2 diabetes mellitus.

BACKGROUND

Medication literacy is essential for the safe and effective use of glucose-lowering therapies in adults with type 2 diabetes mellitus (T2DM). Existing instruments insufficiently capture the multidimensional competencies required for long-term medication management, and no validated tool is available for Chinese adults. This study aimed to develop and psychometrically validate the medication literacy scale for glucose-lowering therapy in adults with T2DM (MLSGT-T2DM) based on the Information–Motivation–Behavioral Skills (IMB) model.

METHODS

The study was conducted from December 2024 to November 2025 and divided into three phases. Phase 1: An initial item pool was developed through a comprehensive literature review and semi-structured interviews with 18 patients with T2DM. Phase 2: Two rounds of Delphi expert consultation were conducted with 16 multidisciplinary experts, among whom 10 evaluated the content validity of the scale, and two rounds of cognitive interviews were carried out with 11 patients to assess face validity. Phase 3: The reliability of the scale was tested by internal consistency, split-half reliability, and retest reliability, and the validity of the scale was measured by exploratory factor analysis (EFA = 300) and confirmatory factor analysis (CFA = 276).

RESULTS

EFA supported a six-factor structure nested within three IMB dimensions (information, motivation, behavioral skills). CFA confirmed good model fit (χ²/df = 2.264, CFI = 0.924, TLI = 0.914, RMSEA = 0.068, SRMR = 0.056). Convergent and discriminant validity were satisfactory. Reliability indices demonstrated strong internal consistency (Cronbach’s α = 0.902; McDonald’s ω = 0.904), acceptable split-half reliability (0.766), and high test–retest stability (ICC = 0.898). The final MLSGT-T2DM comprises 24 items.

CONCLUSION

The MLSGT-T2DM is a psychometrically robust and theoretically grounded instrument for assessing glucose-lowering medication literacy among Chinese adults with T2DM. Its multidimensional structure enables precise identification of knowledge, motivational, and behavioral skill gaps, supporting targeted patient education and more effective diabetes self-management interventions.