Review: Which patients with diabetes should receive which antiplatelet agents?

Abstract

Patients with diabetes mellitus tend to have activated blood platelets, and increased circulating levels of co-factors (fibrinogen, von Willebrand factor) which promote platelet adhesion, aggregation and thrombosis. Systematic reviews of randomised controlled trials of antiplatelet agents show that antiplatelet agents reduce the risk of serious vascular events (myocardial infarction, stroke or death) by about one-quarter in patients with symptomatic vascular disease (secondary prevention), including those with diabetes. So, secondary prevention with an antiplatelet agent (aspirin, clopidogrel, or dipyridamole) should be considered in all diabetic patients with symptomatic vascular disease. Systematic reviews of randomised controlled trials of aspirin in primary prevention show a similar proportional reduction in coronary heart disease events, but not in stroke or death. The excess of adverse events for aspirin (haemorrhagic stroke, major gastrointestinal bleeds), which is unrelated to risk of cardiovascular disease, results in a lower risk: benefit ratio in primary prevention, and is also less cost-effective when aspirin is prescribed. Current SIGN guidelines recommend that aspirin be considered for primary prevention of coronary heart disease in diabetic or non-diabetic persons whose coronary risk is formally estimated to be ≥ 2% per year (in practice, over 80% of diabetic adults without symptomatic vascular disease). Discussions between clinicians and patients should address the potential benefits and harms of aspirin in primary prevention, as well as patient preferences. Further trials are required to identify subgroups in whom primary prevention is most beneficial.