Psychological well-being and quality of life in Type 2 Diabetes Mellitus: investigating psychosocial determinants, barriers to physical activity, and the impact of a walking-based randomised controlled trial

This thesis examined the determinants of QoL and the effectiveness of walking-based in terventions in adults with T2DM across the UK and SA. Four sequential studies employed quan titative approaches to investigate how cultural context influences predictors of well-being and in tervention mechanisms. A cross-sectional survey (N = 177) identified depression as the dominant determinant of QoL in both populations, exceeding the influence of clinical indicators such as glycaemic control. Despite differing health beliefs, overall QoL levels were comparable between SA and UK samples. Walking-based exercise was subsequently identified as an intervention target for improving QoL. A systematic review of the international literature revealed only a small number of walking inter vention studies targeting QoL, none of which met the inclusion criteria for methodological rigour or cultural relevance to either country. This absence underscored the need for context-specific intervention research. A twelve-week RCT (N = 92) demonstrated overall health improvements in both countries, including enhanced glycaemic control and reduced psychological distress. However, the mecha nisms of change diverged: UK participants improved through behavioural activation, achieving sustained increases in walking, whereas SA participants showed enhanced emotional well-being and reduced anxiety despite minimal behavioural change. A barriers study (N = 187) further ex plained these findings, revealing environmental and familial constraints as primary obstacles to physical activity in SA, alongside an inverse association between perceived benefits and activity levels. Collectively, these studies demonstrate that identical interventions can operate through culturally distinct pathways. Effective diabetes management requires context-sensitive design that recognises culture as an active determinant shaping how health improvements occur.