Type 2 Diabetes in Younger Adults

Background: The rising prevalence of obesity and sedentary behaviour has lead to a substantial increase in the number of younger adults (<45 years) developing Type 2 diabetes (T2DM). The amount of time spent sitting (sedentary) has been identified as a risk factor for T2DM which, if targeted, has the potential to prevent T2DM. Aims: 1) To extensively phenotype younger adults with T2DM; 2) To conduct a systematic review and meta-analysis to investigate the relationship between sedentary time, T2DM, cardiovascular disease, cardiovascular and all-cause mortality; 3) To develop the Sedentary Time ANd Diabetes (STAND) structured education programme, designed to reduce sedentary time in younger adults at risk of T2DM and use data from the baseline cohort to describe the prevalence of undiagnosed T2DM in this study population; 4) To assess the effectiveness of the STAND intervention to reduce sedentary behaviour. Key findings: 1) T2DM in younger adults is a associated with an adverse metabolic profile: hyperlipidaemia, vitamin D deficiency, pro-inflammatory state, low physical activity and fitness. Cardiac magnetic resonance imaging demonstrated reduced diastolic strain which was present in the T2DM but not obese or lean control groups. 2) Excess sedentary time was positively associated with diabetes, cardiovascular events, cardiovascular mortality and all-cause mortality. 3) Previously undiagnosed T2DM was present in 4.7% of 193 participants recruited for the STAND randomised controlled trial. 4) The STAND intervention did not significantly reduce sedentary time in the intervention group compared to the control group (p=0.43). Conclusion: This thesis assesses the impact of T2DM on the individual (Chapter Two, Three), quantifies the risk associated with excess sedentary time (Chapter Four) and examines the effectiveness of the STAND programme to reduce sedentary time in younger adults with risk factor for T2DM (Chapters Five to Eight). Recommendations are provided for future research and clinical practice to promote the prevention of T2DM in younger adults.