title: Hypothetical midlife interventions in women and risk of type 2 diabetes.
abstract: BACKGROUND
  Randomized trials have examined short-term effects of lifestyle interventions for diabetes prevention only among high-risk individuals. Prospective studies have examined the associations between lifestyle factors and diabetes in healthy populations but have not characterized the intervention. We estimated the long-term effects of hypothetical lifestyle interventions on diabetes in a prospective study of healthy women, using the parametric g-formula.
  
  
  METHODS
  Using data from the Nurses' Health Study, we followed 76,402 women from 1984 to 2008. We estimated the risk of type 2 diabetes under eight hypothetical interventions: quitting smoking, losing weight by 5% every 2 years if overweight/obese, exercising at least 30 minutes a day, eating less than three servings a week of red meat, eating at least two servings a day of whole grain, drinking two or more cups of coffee a day, drinking five or more grams of alcohol a day, and drinking less than one serving of soda a week.
  
  
  RESULTS
  The 24-year risk of diabetes was 9.6% under no intervention and 4.3% when all interventions were imposed (55% lower risk [95% confidence interval = 47 to 63%]). The most effective interventions were weight loss (24% lower risk), physical activity (19%), and moderate alcohol use (19%). Overweight/obese women would benefit the most, with 10.8 percentage point reduction in 24-year risk of diabetes. The validity of these estimates relies on the absence of unmeasured confounding, measurement error, and model misspecification.
  
  
  CONCLUSIONS
  A combination of dietary and nondietary lifestyle modifications, begun in midlife or later in relatively healthy women, could have prevented at least half of the cases of type 2 diabetes in this cohort of U.S. women.
authors.affiliation: Department of Global Health and Population, Harvard School of Public Health, Boston, MA 02115, USA. gdanaei@hsph.harvard.edu
authors.forename: Goodarz
authors.initials: G
authors.lastname: Danaei
authors.forename: An
authors.initials: A
authors.lastname: Pan
authors.forename: Frank B
authors.initials: FB
authors.lastname: Hu
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernán
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000517:prevention & control*; D004032:Diet; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D053208:Kaplan-Meier Estimate; D008019:Life Style; D008875:Middle Aged; D015233:Models, Statistical; D009010:Monte Carlo Method; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D016540:Smoking Cessation; D011795:Surveys and Questionnaires; D015431:Weight Loss