OBJECTIVES: To conduct initial analyses and examine ways in which depression and anxiety are associated with outcomes after participation in the Healthy Living Course (HLC), an early-intervention diabetes prevention program for adults with prediabetes. DESIGN: Randomised controlled study using pre-intervention and postintervention measures to examine relationships between depression, anxiety and diabetes-related program outcomes. PARTICIPANTS AND SETTING: 185 adults from urban and rural Victoria with prediabetes who had completed the HLC program and for whom postintervention measure data were available. Data were collected between 15 June 2006 and 15 June 2008. MAIN OUTCOME MEASURES: Baseline and postintervention scores on mood (anxiety, depression), biochemical (fasting plasma glucose, oral glucose tolerance), anthropometric (body mass index [BMI], waist circumference), cognitive (self-efficacy, diabetes knowledge) and behavioural (healthy eating, physical activity) measures; correlations between these measures. RESULTS: The intervention alleviated depression, and improved eating patterns and scores on cognitive, anthropometric and biochemical measures. Cultural group and sex did not influence most results. Baseline mood was not associated with anthropometric or biochemical outcomes; however, more positive baseline mood factors were associated with activity changes, and with greater subsequent activity rates, self-efficacy and diabetes knowledge. In turn, baseline self-efficacy was associated with postintervention healthy eating. Changes towards healthier eating correlated with anthropometric and biochemical changes, while baseline cognitive measures were also associated with physiological outcomes. As expected, reductions in BMI and waist circumference were related to biochemical changes. CONCLUSION: Our findings highlight the importance of assessing mood factors in prediabetes, and the need to develop theoretical models of change mechanisms for mood in health outcomes.