Research Article Can the Onset of Type 2 Diabetes Be Delayed by a Group-Based Lifestyle Intervention in Women with Prediabetes following Gestational Diabetes Mellitus (GDM)? Findings from a Randomized Control Mixed Methods Trial Angela O’Dea, 1 Marie Tierney, 1 Brian E. McGuire, 2 John Newell, 3 Liam G. Glynn, 4 Irene Gibson, 5 Eoin Noctor, 1 Andrii Danyliv, 6 Susan B. Connolly, 7 and Fidelma P. Dunne 1 1 School of Medicine, Clinical Sciences Institute, National University of Ireland Galway, Galway, Ireland 2 School of Psychology, National University of Ireland Galway, Galway, Ireland 3 HRB Clinical Research Facility, National University of Ireland Galway, Galway, Ireland 4 Discipline of General Practice, School of Medicine, National University of Ireland Galway, Galway, Ireland 5 Cro´ı–e West of Ireland Cardiac Foundation, Cro´ı Heart and Stroke Centre, Moyola Lane, Newcastle, Galway, Ireland 6 J.E. Cairnes School of Business & Economics, National University of Ireland Galway, Cairnes Building, Galway, Ireland 7 Cardiovascular Medicine, International Centre for Circulatory Health, Imperial College London, London W2 1LA, UK Correspondence should be addressed to Angela O’Dea; angela.odea226@gmail.com Received 22 March 2015; Accepted 7 July 2015 Academic Editor: Ike S. Okosun Copyright © 2015 Angela O’Dea et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective. To evaluate a 12-week group-based lifestyle intervention programme for women with prediabetes following gestational diabetes (GDM). Design. A two-group, mixed methods randomized controlled trial in which 50 women with a history of GDM and abnormal glucose tolerance postpartum were randomly assigned to intervention ( = 24) or wait control ( = 26) and postintervention qualitative interviews with participants. Main Outcome Measures. Modifiable biochemical, anthropometric, behavioural, and psychosocial risk factors associated with the development of type 2 diabetes. e primary outcome variable was the change in fasting plasma glucose (FPG) from study entry to one-year follow-up. Results. At one-year follow-up, the intervention group showed significant improvements over the wait control group on stress, diet self-efficacy, and quality of life. ere was no evidence of an effect of the intervention on measures of biochemistry or anthropometry; the effect on one health behaviour, diet adherence, was close to significance. Conclusions. Prevention programmes must tackle the barriers to participation faced by this population; home-based interventions should be investigated. Strategies for promoting long-term health self-management need to be developed and tested. 1. Introduction Women with a history of gestational diabetes (GDM) are at increased risk of developing type 2 diabetes compared to those with normoglycaemic pregnancies [1]. Studies inves- tigating glucose function in the early postnatal period have shown the prevalence of type 2 diabetes to be as high as 38% in the first year postpartum [2] and as high as 60% in women followed for up to 16 years postpartum [3]. e postpartum period is a very important time in determining the future risk of type 2 diabetes in women with GDM; thus there is a strong rationale for preventive interventions at this time. Some risk factors associated with the development of type 2 diabetes are nonmodifiable such as such as age, ethnicity, or a family history of diabetes. However, some risk factors such as weight, elevated blood glucose, and triglycerides are potentially modifiable though diet, exercise, and lifestyle change [4]; for example, modest weight loss has been shown to be effective in reducing the risk of developing type 2 diabetes in at-risk populations [5]. Hindawi Publishing Corporation Journal of Diabetes Research Volume 2015, Article ID 798460, 11 pages http://dx.doi.org/10.1155/2015/798460