Obesity is associated with increased mortality in the general population but, paradoxically, with decreased mortality in persons with diabetes.
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.
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.
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.”