Type 2 diabetes prevention from research to practice : the SLIMMER lifestyle intervention

INTRODUCTION Diabetes is a worldwide epidemic, causing a high disease and economic burden. Type 2 diabetes, the most common form of diabetes, is associated with overweight and obesity and an unfavourable lifestyle, including unhealthy diet and physical inactivity. Over the last two decades, many large-scale experimental trials have shown that type 2 diabetes can be delayed or prevented by lifestyle modification in high-risk subjects. This evidence has been translated and implemented in interventions in real-world settings, however, no (cost)effective diabetes prevention programme in Dutch primary health care was available at the start of the current project in 2008. Therefore the SLIMMER study (SLIM iMplementation Experience Region Noord- en Oost-Gelderland) was started in which the SLIM intervention, revealing a 47% diabetes risk reduction, was translated to Dutch primary health care. The aim of this thesis was to implement the SLIMMER intervention in Dutch primary health care and to evaluate its (cost)effectiveness and implementation. METHODS In 2010-2011, the SLIMMER intervention was tested for its feasibility and desired impact in a one-year pilot study (n = 31) with process evaluation, including quantitative and qualitative methods. From 2011 to 2014, the SLIMMER intervention was implemented on a larger scale in Dutch public health and primary health care. A randomised controlled trial was conducted (n = 316), including subjects aged 40 to 70 years with impaired fasting glucose or high risk of diabetes. The 10-month SLIMMER intervention involved a dietary and physical activity programme, including case management and a maintenance programme. The control group received usual health care. A logic model of change was composed to link intervention activities with intervention outcomes in a logical order. Primary outcome was fasting insulin. Measurements were performed at baseline and after 12 and 18 months and covered quality of life, clinical and metabolic risk factors (e.g. glucose tolerance, serum lipids, body fatness, and blood pressure), and eating and physical activity behaviour. Furthermore, a process evaluation including quantitative and qualitative methods was conducted. Data on process indicators (recruitment, reach, dose received, acceptability, implementation integrity, and applicability) were collected in semi-structured interviews with health care professional (n = 45) and intervention participant questionnaires (n = 155). Moreover, cost-effectiveness analyses were performed from both a societal and a health care perspective. Participants completed questionnaires to assess health care utilisation, participant out-of-pocket costs, and productivity losses. RESULTS The pilot study showed that participants lost on average 3.5 kg (p = 0.005) of their body weight. Both participants and health care professionals were satisfied with the intervention, which was implemented as planned and appeared to be suitable for application in practice. Refinements were identified and made prior to further implementation. The randomised controlled trial showed that after 12 and 18 months, the intervention group significantly improved weight (β=-2.7 kg (95% CI: -3.7;-1.7) and β=-2.5 kg (95% CI: -3.6;-1.4), respectively), and fasting insulin (β=-12.1 pmol/l (95% CI: -19.6;-4.6) and β=-8.0 pmol/l (95% CI: -14.7;-0.53), respectively) compared with the control group. Intervention subjects improved weight and glucose tolerance, independent of manner of recruitment (laboratory glucose test or Diabetes Risk Test). Furthermore, intake of total and saturated fat decreased and fibre intake increased in the intervention group compared with the control group, both at 12 and 18 months (p CONCLUSION In conclusion, this study showed that a thorough preparation of translation and implementation has led to a cost-effective intervention to prevent type 2 diabetes which is feasible to implement in Dutch primary health care. In fact, our clinical effects were larger than those in most other real-world intervention programmes, and most effects sustained at 18 months. Furthermore, we showed that a higher intervention dose and participant acceptability were associated with improved health outcomes and dietary behaviour. Further research is needed on effects and costs over longer follow-up, effective intervention components, and consequences of suggested adaptations of the programme on intervention effectiveness. The results of this study provide valuable insights that can contribute to structural embedding and funding of effective diabetes prevention programmes in Dutch primary health care.