title: Body mass index, diabetes, and mortality in French women: explaining away a "paradox".
abstract: BACKGROUND
  Obesity is associated with increased mortality in the general population but, paradoxically, with decreased mortality in persons with diabetes.
  
  
  METHODS
  Among 88,373 French women participating in the E3N-EPIC study who were free of diabetes in 1990, we estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) of mortality for body mass index (BMI) levels by diabetes status.
  
  
  RESULTS
  During an average 16.7 years of follow-up, 2421 cases of diabetes were identified and 3750 deaths occurred. For overweight/obese versus normal-weight women, the HR of mortality was 1.42 (95% CI = 1.32-1.53) in women without diabetes and 0.69 (0.40-1.18) in women with incident diabetes. As BMI increased, mortality among women without diabetes increased and that among women with diabetes decreased.
  
  
  CONCLUSIONS
  We found the obesity "paradox" among women with and without incident diabetes in the same population. Selection bias may be a simple explanation for this "paradox."
authors.affiliation: From the aDepartment of Epidemiology, Harvard School of Public Health, Boston, MA; bCenter for Research on Population Health, National Institute of Public Health, Cuernavaca, Mexico; cNational Institute of Health and Medical Research (Inserm), Center for Research in Epidemiology and Population Health (CESP), U1018, Gustave-Roussy Cancer Institute, Villejuif, France; dParis-South University, UMRS 1019, Villejuif, France; eDepartment of Biostatistics, Harvard School of Public Health, Boston, MA; fHarvard-MIT Division of Health Sciences and Technology, Boston, MA.
authors.forename: Martin
authors.initials: M
authors.lastname: Lajous
authors.forename: Anne
authors.initials: A
authors.lastname: Bijon
authors.forename: Guy
authors.initials: G
authors.lastname: Fagherazzi
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Boutron-Ruault
authors.forename: Beverley
authors.initials: B
authors.lastname: Balkau
authors.forename: Françoise
authors.initials: F
authors.lastname: Clavel-Chapelon
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernán
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D015897:Comorbidity; D016001:Confidence Intervals; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000401:mortality*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology / Q000401:mortality*; D050177:Overweight / Q000453:epidemiology / Q000401:mortality; D016016:Proportional Hazards Models; D012307:Risk Factors; D015983:Selection Bias