Evaluation of the Effectiveness of Lifestyle Interventions in theprimary prevention of diabetes mellitus type II in high-riskindividuals

Abstract

Background/research question: The increasing prevalence of type II diabetes mellitus (T2DM) raises the question as to whether lifestyle interventions (diet/exercise) can delay or prevent the manifestation of T2DM and reduce the risk of micro- and macrovascular complications and premature death in high-risk individuals. The primary aim of this thesis was to determine whether systematic reviews exist that are able to answer the research question and thus provide a basis for the production of evidence-based health information (EBHI). Secondly, evidence on patient relevant outcomes like cardiovascular disease and mortality on the basis of individual RCTs and epidemiological studies was to be collected. Methods: PubMed, the Cochrane Library and DARE have systematically been searched for systematic reviews of controlled trials (CTs) in June 2013. The DIMDI, NICE and AHRQ websites were manually searched. Systematic reviews were included if they met predefined inclusion criteria and achieved an Oxman & Gyuatt Index ≥ 5. Two researchers independently screened 710 titles/abstracts and the resulting 48 full-text articles. Results: 9 relevant systematic reviews have been identified, of which 4 had the required quality. They differed in terms of the populations, interventions and outcomes included, as well as the search date. The most appropriate review included 11 randomized CTs in a meta-analysis: The pooled hazard ratio versus controls was 0.51 (95% CI 0.43-0.62). Assuming an annual diabetes incidence of 11% as in the US Diabetes Prevention Program the calculated absolute risk of diabetes in the intervention groups would be 5.61% (95% CI 4.73- 6.82). Significant reductions in long term adverse health outcomes like CVD risk, CVD or all-cause mortality could neither be found in the 4 identified reviews nor in the individual RCTs. However, long term follow-up data of individual RCTs indicated benefits of lifestyle interventions in terms of microvascular complications like diabetic retinopathy and HRQoL. Conclusions: Lifestyle interventions can prevent or delay the diagnosis of T2DM in high-risk individuals. The findings translate into an estimated effect of about 5 out of 100 individuals by reducing an assumed annual diabetes progression rate of 11 out of 100 to about 6 out of 100 individuals. The systematic procedure to find the best available external evidence resulted in a suitable basis for the production of EBHI on diabetes prevention in high-risk individuals. Whether the applied evaluation method is the most suitable for creating EBHI is worth consideration.