An extensive collaboration of authors comprising the ASCEND Study Collaborative Group explored the association between increased omega-3 fatty acid intake and decreased cardiovascular disease in patients with diabetes, which was established previously only with observational studies. This association had not been supported by randomized, placebo-controlled trials and, therefore, remained unsubstantiated. The study, which was featured in February 2019 in Diabetes in Control Media News, highlights a study published in October 2018 in the New England Journal of Medicine.

The study team explored the primary outcome of a potentially decreased risk of a first serious vascular event as evidenced by vascular death, transient ischemic attack, stroke, or nonfatal myocardial infarction in 15,480 patients diagnosed with diabetes who received supplemental omega-3 fatty acids. In order to be randomly assigned to receive 1-gram capsules containing either omega-3 fatty acids or a matching placebo of olive oil daily, individuals had to be diagnosed with diabetes but show no evidence of atherosclerotic cardiovascular disease. Secondary outcomes included any arterial revascularization or first serious vascular event. Researchers established a mean follow-up of 7.4 years

The results of this study suggest that omega-3 fatty acid supplementation does not significantly influence the risk of major cardiovascular events in patients with diabetes. In the study cohort, serious vascular events occurred in 8.9% of patients (n = 689) in the omega-3 fatty acid group and in 9.2% (712) of patients in the placebo group (rate ratio, 0.97; 95% CI, 0.87-1.08; P = .55).

Furthermore, secondary outcomes of a serious vascular event or revascularization occurred in 11.4% of omega-3–supplemented patients (n = 882) and 11.5% of placebo patients (n = 887), respectively (rate ratio, 1.00; 95% CI, 0.91-1.09). The authors noted that there were no significant differences in the rates of nonfatal serious adverse events in either group; however, death from any cause occurred in 9.7% (752) of the omega-3–supplemented patients and in 10.2% (788) of the placebo group (rate ratio, 0.95; 95% CI, 0.86-1.05).

The authors noted, “These findings, together with results of earlier randomized trials involving patients with and those without diabetes, do not support the current recommendations for routine dietary supplementation with n–3 fatty acids to prevent vascular events.”
 
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