Diabetes Mellitus, Race, and Effects of Omega-3 Fatty Acids on Incidence of Heart Failure Hospitalization

Objectives: The primary aim was to evaluate whether prevalent type 2 diabetes (T2D) modifies the effects of omega-3 supplementation on heart failure (HF) hospitalization. The secondary aim was to examine if race modifies the effects of omega-3 supplements on HF risk.

Background: It is unclear whether race and T2D modify the effects of omega-3 supplementation on the incidence of HF.

Methods: In this ancillary study of the parent VITAL (Vitamin D and Omega-3 Trial)-a completed randomized trial testing the efficacy of vitamin D and omega-3 fatty acids on cardiovascular diseases and cancer, we assessed the role of T2D and race on the effects of omega-3 supplements on the incidence of HF hospitalization (adjudicated by a review of medical records and supplemented with a query of Centers for Medicare and Medicaid Services data).

Results: When omega-3 supplements were compared with placebo, the HR for first HF hospitalization was 0.69 (95% CI: 0.50-0.95) in participants with prevalent T2D and 1.09 (95% CI: 0.88-1.34) in those without T2D (P for interaction = 0.019). Furthermore, prevalent T2D modified the effects of omega-3 fatty acids on the incidence of recurrent HF hospitalization (HR: 0.53; 95% CI: 0.41-0.69 in participants with prevalent T2D vs HR: 1.07; 95% CI: 0.89-1.28 in those without T2D; P interaction <0.0001). In our secondary analysis, omega-3 supplementation reduced recurrent HF hospitalization only in Black participants (P interaction race × omega-3 = 0.0497).

Conclusions: Our data show beneficial effects of omega-3 fatty acid supplements on incidence of HF hospitalization in participants with T2D but not in those without T2D, and such benefit appeared to be stronger in Black participants with T2D. (Intervention With Vitamin D and Omega-3 Supplements and Incident Heart Failure; NCT02271230; Vitamin D and Omega-3 Trial [VITAL]; NCT01169259 [parent study]).