ASCEND (A Study of Cardiovascular Events iN Diabetes) is a randomised trial looking at the effects of aspirin and of omega-3 fatty acids (fish oils) in people with diabetes. ASCEND recruited 15,500 people with diabetes (either type 1 or type 2) who did not have known vascular disease or recent cancer when they started the trial, and these people were randomly allocated to take 100mg aspirin daily or placebo (dummy) and 1 gram capsules containing naturally occurring omega-3 fatty acids ("fish-oils") or placebo capsules containing olive oil. ASCEND aimed to provide the first reliable evidence about the effects of aspirin and of omega-3 fatty acids in diabetes both for preventing heart disease and strokes and also for cancer prevention.
Funding for the study was secured from the British Heart Foundation, packaged aspirin and matching placebo was provided by Bayer AG and packaged omega-3 fatty acid supplements and matching placebo capsules by Mylan (and formerly from Abbott Pharmaceuticals and before that from Solvay).
The results of the ASCEND trial were announced in August 2018:
Aspirin prevented serious vascular events including heart attacks, strokes and mini strokes in patients with diabetes who did not already have cardiovascular disease, but it also increased the risk of major bleeds, mainly from the gastrointestinal tract, so overall there was no clear benefit. It had been suggested that low-dose aspirin might protect against cancer, but there was no reduction in any cancers. We are continuing to follow the participants to see whether any benefits appear later.
Effects of Aspirin for Primary Prevention in People with Diabetes Mellitus
Omega-3 fatty acids
Fish oil supplements do not prevent heart attacks or strokes in patients with diabetes. This is in line with previous randomised trials in other types of patient at increased risk of cardiovascular events which also showed no benefit of fish oil supplements. There is no justification for recommending fish oil supplements to protect against cardiovascular events.
Effects of n−3 Fatty Acid Supplements in Diabetes Mellitus
Effects of aspirin on dementia and cognitive impairment in the ASCEND trial presented at the American Heart Association (AHA) Scientific Sessions, 15 November 2021.