Educational intervention based on the extended parallel process model improves adherence to diabetic diet and glycaemic control indices: a randomised, double-blind, controlled, factorial field trial

Nutritional education is pivotal in the medical nutritional therapy of type 2 diabetes mellitus (T2DM). The extended parallel process model (EPPM) is a health education method for inducing desirable health behaviours. The present study aimed to investigate the effect of nutritional education based on the EPPM in T2DM patients on knowledge, attitude, practice, anthropometric indices, glycaemic factors, lipid profile and adherence to the diabetic diet. A randomised, double-blind, controlled, factorial field trial was designed for T2DM patients aged 30-59 years (n 88). Participants were randomly allocated into four groups to receive EPPM-based nutritional education through gain framed message (GFM), loss framed message (LFM), their combination (G\LFM) or usual diabetic education in the control group (CG). Participants were assessed before and after the study duration. After 3 months of intervention, eighty participants finished the study. The EPPM-based intervention increased participants' knowledge, behavioural intention, perceived sensitivity, severity, self-efficacy (P < 0·001 for all) and response efficacy (P = 0·029) in comparison with CG. GFM (P = 0·004) and G\FLM (P = 0·034) reduced carbohydrate intake and LFM (P = 0·034) and G\LFM (P = 0·047) decreased fat intake. Between-group analysis indicated interventions reduced weight (P = 0·046), BMI (P = 0·038), fasting blood sugar (P = 0·030), 2-hour postprandial blood glucose (P = 0·027) and TAG (P = 0·002) in comparison with the CG. Results were NS for protein intake, waist and hip circumference, waist:hip ratio, HbA1c, total cholesterol, LDL and HDL. Nutritional education based on EPPM could increase the knowledge and awareness of T2DM patients. Also, it could be beneficial for blood glucose amendment. Further investigations are recommended.