Psychometric Validation of the Chinese Version of the Diabetes Health Literacy Scale Among Adults with Type 2 Diabetes Mellitus: Application of Factor Analysis and Item Response Theory

Background: Diabetes health literacy is a critical determinant of a patient's ability to effectively self-manage the condition, and its accurate assessment is paramount for developing targeted interventions. This study aims to translate and validate the reliability and validity of the Chinese version of the Diabetes Health Literacy Scale (DHLS) among Chinese patients with type 2 diabetes mellitus based on factor analysis and item response theory (IRT) models. Methods: The cross-sectional study was conducted among 251 adult patients with type 2 diabetes mellitus admitted to a tertiary hospital in Wuhu City. The 14-item DHLS was administered to all participants. Reliability was evaluated using Cronbach's alpha. The three-factor structure of the scale was assessed through both exploratory and confirmatory factor analysis (EFA/CFA). Furthermore, the Graded Response Model from IRT was employed to analyze item discrimination, difficulty parameters, and the scale information function. Results: The Chinese version of the DHLS demonstrated excellent overall reliability (Cronbach's alpha = 0.938). Both EFA and CFA strongly supported the original three-factor structure (informational, computational, and communicative literacy). Convergent validity was satisfactory, with all subscales achieving the average variance extracted (AVE) > 0.50, and composite reliability values > 0.70. Discriminant validity was also confirmed, as the square roots of the AVE for each subscale exceeded the inter-construct correlations. IRT analysis confirmed that all 14 items had satisfactory discrimination parameters and exhibited monotonic increasing difficulty patterns. Importantly, the total information curve revealed that the scale provides the most precise measurement for individuals with moderate levels of health literacy. Conclusion: The Chinese version of the DHLS is a valid and reliable instrument with robust psychometric properties. Its application can facilitate the development of targeted interventions, ultimately improving diabetes management outcomes.