Effectiveness of Theory-Based Intervention on Knowledge Level, Psychological Constructs, Metabolic Index and Physical Activity Status in Patients with Type 2 Diabetes: Application of the Health Action Process Approach (HAPA) Model

Objective: The aim of the study was to determine the effect of the educational intervention based on the health action process approach (HAPA) model on the level of knowledge, metabolic indicators, psychological constructs and physical activity status in type 2 diabetes (T2D) patients in 2022–2023. Material and methods: The present study was a randomized controlled trial and 100 T2D patients were equally assigned to experimental and control groups using multistage random sampling. The educational program included six online sessions, targeted pamphlets, educational audio files and reminder messages. Data were collected before and 3 months after intervention with demographic items, awareness scale, constructs of HAPA model, IPAQ-s, HbA1c and fasting blood glucose (FBG). Data were entered to SPSS 25.0 and analyzed with chi-square, ANOVA and ANCOVA. Results: After controlling the effect of the pre-test variable, the mean of the HAPA model constructs and mean of physical activity improved significantly in posttest. In addition, educational intervention explained 30.2%, 57.8%, 33.2%, 64.4%, 76.3%, 25.3%, 24.6%, 36.1% and 36.9% of the variance of health awareness, risk perception, outcome expectancy, action self-efficacy, maintenance self-efficacy, action plan, coping plan, behavioral intention and physical activity, respectively. In addition, the mean of FBG and HbA1c in the experimental group improved significantly after the intervention by controlling the pre-test effect (p < 0.001). Conclusions: Providing theory-based educational interventions through the web and mobile can increasingly promote the effectiveness of cognitive behavioral interventions and facilitate the process of behavior change in T2D.