No benefit from the obesity paradox for diabetic patients with heart failure

Abstract

Aims: Paradoxically, obesity is associated with survival in heart failure (HF). Whether this is true for HF patients with comorbid type-2 diabetes (T2D) remains uncertain. Our aim was to address this issue in diabetic patients by collecting correlates for body mass index (BMI) and long-term mortality. Method and results: Both BMI and survival after a mean follow-up of 4.3 ± 3.0 years (up to 10 years) were assessed for 2527 ambulatory patients (66.3% men; mean age 69 ± 12.3 years). A total of 1102 (43.6%) patients had T2D and ischaemic aetiology of HF was present in 47.8%; mean left ventricular ejection fraction was 38 ± 16%. Based on BMI scores, patients were categorized as either underweight, normal, overweight, or obese. A significant survival interaction was observed between BMI and T2D. Smooth spline curves for the estimation of risk of all-cause and cardiovascular death showed the classic obesity paradox, with reduced mortality as BMI increased in non-diabetics; for T2D patients this pattern was lost. After adjustment for age and sex, hazard ratios for low-weight and obesity were: 2.04 [95% confidence intervals (CI) 1.50–2.78, P < 0.001] and 0.76 (95% CI 0.58–0.99, P = 0.04), respectively, for non-T2D patients; and 1.30 (95% CI 0.77–2.19, P = 0.32) and 0.99 (95% CI 0.78–1.26, P = 0.95), respectively, for T2D patients. Multivariate analyses for mortality (including BMI as a continuous variable) were significant for non-diabetic patients only. Conclusions: In patients with HF, but without T2D, the obesity paradox was present; however, T2D removed this phenomenon. Advice about weight loss for obese diabetic patients with HF requires further research.