Obesity paradox: Comparison of heart failure patients with and without comorbid diabetes

Background Diabetes is a common comorbid condition in patients with heart failure and is strongly associated with poor outcomes. Patients with heart failure who have diabetes are more likely to be obese than are those without diabetes. Obesity is positively associated with survival in patients with heart failure, but how comorbid diabetes influences the relationship between obesity and favorable prognosis is unclear. Objective To explore whether the relationship between body mass index and survival differs between patients with heart failure who do or do not have diabetes. Methods The sample consisted of 560 ambulatory patients with heart failure (mean age, 66 years; mean body mass index, 32; diabetes, 41%). The association between body mass index and all-cause mortality was examined by using multivariate Cox proportional hazards regression after adjustments for covariates. Results In patients without diabetes, higher body mass index was associated with a lower risk for all-cause mortality after adjustments for covariates (hazard ratio, 0.952; 95% CI, 0.909-0.998). In patients with diabetes, body mass index was not predictive of all-cause death after adjustments for covariates. Conclusion Obesity was a survival benefit in heart failure patients without comorbid diabetes but not in those with comorbid diabetes. The mechanisms underlying the difference in the relationship between obesity and survival due to the presence of diabetes in patients with heart failure need to be elucidated.