Atherosclerotic cardiovascular disease (CVD) is common in patients with diabetes, and antiplatelet therapy has been the cornerstone of preventative therapy for many years. The majority of the evidence for the use of aspirin in patients with diabetes comes from subgroup analysis of major secondary prevention trials. Secondary prevention data from the Antiplatelet Trialist’s Collaboration meta-analysis suggests that the benefit derived from aspirin is similar in diabetic and non-diabetic populations. In the general population, data from primary prevention studies have shown the benefit of aspirin in terms of cardiovascular mortality, but there is little evidence to suggest that aspirin is beneficial in terms of total or cardiovascular mortality for primary prevention in a diabetic population. Clopidogrel may have advantages over aspirin and combined therapy may be superior for certain types of coronary artery disease and stroke, although this is offset by an increased risk of haemorrhage in the latter setting. The use of aspirin in the prevention of CVD in patients with diabetes should therefore be focused on those with a history of vascular events or aggressively treated hypertension.