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Background: Lifestyle interventions have been shown to delay or prevent the onset of type 2 diabetes among high risk adults. A better understanding of the variability in physiological responses would support the matching of individuals with the best type of intervention in future prevention programmes, in order to optimize risk reduction. The purpose of this study was to determine if phenotypic characteristics at baseline or following a 12 weeks lifestyle intervention could explain the inter-individual variability in change in glucose tolerance in individuals with high risk for type 2 diabetes. Methods: In total, 285 subjects with normal glucose tolerance (NGT, FINDRISC score > 12), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were recruited for a 12 weeks lifestyle intervention. Glucose tolerance, insulin sensitivity, anthropometric characteristics and aerobic fitness were measured. Variability of responses was examined by grouping participants by baseline glycemic status, by cluster analysis based on the change in glucose tolerance and by Principal Component Analysis (PCA). Results: In agreement with other studies, the mean response to the 12 weeks intervention was positive for the majority of parameters. Overall, 89% improved BMI, 80% waist circumference, and 81% body fat while only 64% improved fasting plasma glucose and 60% 2 h glucose. The impact of the intervention by glycaemic group did not show any phenotypic differences in response between NGT, IFG, and IGT. A hierarchical cluster analysis of change in glucose tolerance identified four sub-groups of "responders" (high and moderate) and "non-responders" (no response or deteriorated) but there were few differences in baseline clincal and physiological parameters or in response to the intervention to explain the overall variance. A further PCA analysis of 19 clinical and physiological univariables could explain less than half (48%) of total variability. Conclusion: We found that phenotypic characteristics from standard clinical and physiological parameters were not sufficient to account for the inter-individual variability in glucose tolerance following a 12 weeks lifestyle intervention in inidivuals at high risk for type 2 diabetes. Further work is required to identify biomarkers that complement phenotypic traits and better predict the response to glucose tolerance.

Background: With the global escalation of type 2 diabetes and evidence consistently showing that its onset can be prevented or delayed by changing lifestyle behaviours, there is an urgent need to translate practical, affordable and acceptable interventions from the research setting into the real world. One such approach to lifestyle interventions might be the introduction of a programme in which the individual is provided with choice and facilitated to 'self-select' an exercise programme. Previous research has shown that this is likely to be less resource intensive, an essential requirement for success outside the controlled research environment, while at the same time promoting positive responses relating to adherence, competence and self-efficacy, essential attributes for long-term success. Through a two-group parallel-randomised controlled trial, this study aims to assess the clinical and psychological impact of the DEXLIFE 'self-selected' lifestyle modification programme in adults at risk of developing type 2 diabetes., Methods/design: A total of 360 subjects at risk of developing type 2 diabetes are randomly assigned in a 1:3 ratio to a control (n = 90) or intervention arm (n = 270). Randomization is stratified by age, sex and body mass index. The control arm receives general information on lifestyle and diabetes risk. The intervention group participate in a 12 week 'self-selected' supervised exercise training programme accompanied with dietary advice to improve food choices. Participants are given access to Dublin City University Sport (an on-campus gym) and asked to perform four exercise classes per week. Dublin City University Sport offers over 50 classes per week, many of which are medically supervised. If weight loss is indicated, reduction in total calorie intake by 600 kcal/day is advised. Common to all food plans is <10% saturated fat intake, as well as a dietary fibre intake of >15 g/1000 kcal. Insulin sensitivity is the primary outcome measure. Secondary outcome measures include glucose function, fitness, body composition, anthropometrics, heart rate variability, lipid profiles, blood pressure, physical activity levels, dietary intake and quality of life., Discussion: "Self-selected" lifestyle intervention has not previously been evaluated in type 2 diabetes prevention and if shown to be successful could be implemented in practice immediately., Trial Registration: Current Controlled Trials: ISRCTN66987085.