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Body Mass Index, Diabetes, and Mortality in French Women: Explaining Away a Paradox

Lajous, Martina,b,c; Bijon, Annec,d; Fagherazzi, Guyc,d; Boutron-Ruault, Marie-Christinec,d; Balkau, Beverleyc,d; Clavel-Chapelon, Françoisec,d; Hernán, Miguel A.a,e,f

doi: 10.1097/EDE.0000000000000031
Obesity

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.”

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.

This work was supported by the Mutuelle Générale de l’Education Nationale, French League against Cancer, Gustave Roussy Institute, French Institute of Health and Medical Research, and Inserm-INSP Associated International Laboratory. The validation of type 2 diabetes cases was supported by the European Union (Integrated Project LSHM-CT-2006–037197 in the Framework Program 6 of the European Community) InterAct project. This research was partly supported by NIH grant R01 HL080644. M.L. was supported by the National Council for Science and Technology (CONACYT, Mexico).

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Correspondence: Françoise Clavel-Chapelon, Center for Research in Epidemiology and Population Health, Institut National de la Santé et de la Recherche Médicale U1018, Team 9, Nutrition, Hormones and Women’s Health, Institut Gustave-Roussy, 114 Rue Edouard Vaillant, 94805 Villejuif Cedex, France. E-mail: Francoise.CLAVEL@gustaveroussy.fr.

© 2014 by Lippincott Williams & Wilkins, Inc