Development of a diabetes-related nutrition knowledge questionnaire for individuals with type 2 diabetes mellitus in Singapore

Aim: Diabetes-related nutrition knowledge (DRNK) is essential for the self-care of patients with type 2 diabetes mellitus (T2DM). A specific tool measuring DRNK can help us to understand awareness levels and tailor structured nutrition education programs. Our study aimed to develop a questionnaire to assess DRNK for individuals with T2DM in Singapore. Methods: An expert panel was formed to consolidate in-depth, culturally suitable, and current information on DRNK. A literature review of diabetes self-care knowledge questionnaires was performed to outline the scope of the questionnaire and generate a question pool. User friendliness was tested in the first draft of the questionnaire (n = 21). Then, a second draft was tested for item difficulty, discrimination index, and internal consistency (n = 62). The final draft was examined for construct validity and test–retest reliability (n = 100). Results: The final questionnaire (four sections: 27 questions) was found to be consistent and reliable. The item difficulty scores of the selected questions ranged from difficult to desirable (2–85). There was fair to good internal consistency (Cronbach's alpha: 0.66, 0.79, 0.56, and 0.78 for Sections 1, 2, 3 and 4, respectively) and construct validity (independent t-test: P < 0.001). Questions in the final questionnaire had an average discrimination index of 0.3 (reasonably good). The questionnaire was revealed to have good test–retest reliability (intraclass correlation: 0.82–0.84). Conclusions: The DRNK questionnaire is a valid and reliable measure to complement assessment tools measuring self-efficacy/behaviour in individuals with T2DM living in Singapore.