To develop and psychometrically evaluate a multidimensional Disaster Health Literacy Questionnaire (DHLQ) for diabetic patients in Iran, using advanced item response theory approaches. The questionnaire was designed in the Persian (Farsi) language.

A sequential mixed-methods study incorporating qualitative (scoping review and interviews) and quantitative (psychometric validation) phases.

Diabetes clinics and healthcare centres across Iran (2022–2023).

The study enrolled 570 patients with diabetes (56% female, mean age 45.57±16.33 years) for quantitative validation; 15 experts and 15 patients for qualitative validation.

The psychometric properties evaluated included content validity (using content validity ratio (CVR) and content validity index (CVI)), construct validity (assessed via multidimensional item response theory (MIRT)), and reliability (measured by Cronbach’s alpha and test-retest Kappa). Additionally, item parameters (multidimensional difficulty (MDIFF) and multidimensional discrimination (MDISC)) and model fit indices (RMSEA, CFI and TLI) were examined.

The final 30-item DHLQ demonstrated excellent content validity (scale-level CVI=1; item-level CVI>0.79; CVR>0.49). Cronbach’s alpha for the total scale was 0.606; test-retest reliability showed significant agreement (Kappa=0.35–1, p

The DHLQ is a rigorously validated tool for assessing disaster health literacy in diabetic populations. Its multidimensional structure and strong psychometric properties support its use in clinical and emergency planning contexts to identify literacy gaps and tailor interventions.