Development and empirical evaluation of a dietary intervention programme for individuals with prediabetes based on the health action process approach: A randomised controlled trial

Prediabetes represents a critical window for preventing or delaying the onset of type 2 diabetes, and maintaining a healthy diet is essential. This study evaluated a dietary intervention based on the Health Action Process Approach (HAPA) to improve dietary adherence. Prior to trial implementation, a targeted intervention was developed through a literature search on adherence strategies (e.g., the teach-back method and social network interventions) and interviews identifying local barriers to healthy eating, including low cognition and motivation, limited skills and resources, and lack of supportive environments, and was subsequently evaluated in a randomised controlled trial. Sixty-four residents diagnosed between August 2023 and August 2024 at a health service centre in Bengbu, China, were randomly assigned to two groups (n = 32 each). (1) routine care, (2) HAPA group: including a one-week visual dietary recipe created by photographing meal plate layouts for three meals based on food models, coping strategies for special situations (e.g., holiday gatherings), combined with family and peer support. Changes from baseline to three months were assessed using t-tests, covering disease knowledge, dietary adherence (Chinese Diabetes Management Self-Efficacy Scale [C-DMSES]), acceptability, dietary structure (3-day 24-h recalls and a Food Frequency Questionnaire [FFQ]), proportion meeting fibre intake recommendations (whole grains and legumes, and vegetables), body mass index (BMI), fasting plasma glucose (FPG), and 2-h postprandial glucose (2hPG). The HAPA group showed significant improvements in knowledge, acceptability, adherence scores, proportion meeting whole grains and legumes intake recommendations, BMI, FPG, and 2hPG compared with controls (P < 0.05). Intake of whole grains, legumes, and vegetables was higher, whereas refined grains and starchy were lower (P < 0.05). The intervention improved dietary adherence and structure (increased dietary fibre and reduced refined grains), guiding sustaining healthy eating in people with prediabetes.