Predicting changes in lifestyle and clinical outcomes in preventing diabetes: The Greater Green Triangle Diabetes Prevention Project

ObjectivesTo analyse how psychosocial determinants of lifestyle changes targeted in the Greater Green Triangle Diabetes Prevention Project conducted in Southeast Australia in 2004–2006 predict changes in dietary behaviour and clinical risk factors.MethodsA longitudinal pre-test and post-test study design was used. The group program was completed by 237 people at high risk of type 2 diabetes. Associations between changes in the variables were examined by structural equation modelling using a path model in which changes in psychological determinants for lifestyle predicted changes in dietary behaviours (fat and fibre intake), which subsequently predicted changes in waist circumference and other clinical outcomes. Standardised regression weights are presented, with β = ± 0.1 and β = ± 0.3 representing small and medium associations, respectively.ResultsImprovements in coping self-efficacy and planning predicted improvements in fat (β = − 0.15, p < 0.05 and β = − 0.32, p < 0.001, respectively) and fibre intake (β = 0.15, p < 0.05 and β = 0.23, p < 0.001, respectively) which in turn predicted improvements in waist circumference (β = 0.18, p < 0.01 and β = − 0.16, p < 0.05, respectively). Improvements in waist circumference predicted improvements in diastolic blood pressure (β = 0.13, p < 0.05), HDL (β = − 0.16, p < 0.05), triglycerides (β = 0.17, p < 0.01), and fasting glucose (β = 0.15, p < 0.05).ConclusionsPsychological changes predicted behaviour changes, resulting in 12-month biophysical changes. The findings support the theoretical basis of the interventions.

► Trials rarely report the chain of effects from behaviour change to risk factors.
► The impact of psychological changes on changes in measured risk factors was tested.
► Improvements in coping self-efficacy and coping planning predicted reduction of waist.
► Effects of psychological changes were mediated by changes in dietary behaviours.
► Dietary changes predicted improvements in blood pressure, lipids and fasting glucose.