THEORY AND REALITY: Diabetes mellitus is known to be associated with excess cardiovascular risk. Prescription of antiplatelet agents such as acetylsalicylic acid would thus appear to be warranted. That is the theory, but the reality is much different. A review of the literature provides evidence on the use of acetylsalicylic acid for primary and secondary preventive care, but conclusions are often extrapolated from studies conducted in the general population. EVIDENCE OF A BENEFICIAL EFFECT IN DIABETICS: The HOT study, conducted in hypertensive patients) demonstrated that acetylsalicylic acid at the dose of 75 mg a day, reduced the rate of major cardiovascular events by 15% (p = 0.03) and of myocardial infarction by 36% (p = 0.02) with no effect on stroke. In diabetic patients (n = 1500), the benefit was even more pronounced.The risk of bleeding must be balanced against the beneficial cardiovascular effect. Diabetic retinopathy is not aggravated by aspirin. The data reported in the literature do not however enable any evidenced-based decision on dosing for the diabetic population with numerous cardiovascular risks.