Efficacy of lifestyle education to prevent type 2 diabetes - A meta-analysis of randomized controlled trials

OBJECTIVE - To evaluate the efficacy of lifestyle education for preventing type 2 diabetes in individuals at high risk by meta-analysis of randomized controlled trials, as assessed by incidence and a reduced level of plasma glucose 2 h after a 75-g oral glucose load (2-h plasma glucose). RESEARCH DESIGN AND METHODS - Through an electronic search, 123 studies were identified. A literature search identified eight studies that met strict inclusion criterion of meta-analysis for 2-h plasma glucose and five studies for the incidence of diabetes. All were randomized controlled trials of >= 6 months with lifestyle education that included a dietary intervention. Subjects were adults diagnosed as being at high risk for type 2 diabetes. The difference in mean reduction of 2-h plasma glucose from baseline to the 1-year follow-up and relative risk (RR) of the incidence of diabetes in the lifestyle education group versus the control group were assessed. Overall estimates were calculated using a random-effects model. Those estimates were confirmed by several models, and the possibility of selection bias was examined using a funnel plot. RESULTS - Lifestyle education intervention reduced 2-h plasma glucose by 0.84 mmol/l (95% CI 0.39-1.29) compared with the control group. The 1-year incidence of diabetes was reduced by similar to 50% (RR0.55, 95% CI 0.44-0.69) compared with the control group. Results were stable and little changed if data were analyzed by subgroups or other statistical models. Funnel plots revealed no selection bias. CONCLUSIONS - Lifestyle education was effective for reducing both 2-h plasma glucose and RR in high-risk individuals and may be a useful tool in preventing diabetes.