Recent trial results seem to contradict this general recommendation. Dr Hisao Ogawa et al. published the results of the Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes (JPAD) (JAMA 2008; 300, 2134-41) Trial showing no significant effect of aspirin on a combined endpoint of cardiovascular adverse events including fatal or nonfatal ischemic heart disease, fatal or nonfatal stroke and peripheral artery disease. However, the event rate in this trial was much lower than predicted and therefore the trial was largely underpowered to draw a meaningful conclusion. In addition, secondary endpoints focusing on more severe events like death, MI and stroke exerted a significant effect of aspirin in the entire patient cohort, as did the observation of the primary endpoint in diabetics above the age of 65 years.
The key role of antiplatelet therapy (mainly aspirin) for the secondary prevention of myocardial infarction and strokes is firmly established for high-risk patients with established arterial disease, and the proportional reductions in these cardiovascular events appear to be in the range of 20 to 25%, independent if the patients have diabetes or not. However, many young and middle-aged persons with diabetes do not have manifest arterial disease yet - although they are at a significant cardiovascular risk. Therefore, the substantial persons with uncertainty about the role of aspirin for the prevention of myocardial infarctions and strokes among apparently vascular healthy diabetes will remain until results of ongoing trials focusing on diabetics will be published in the years to come.
Until these results are available, the clinical strategy should include aspirin for primary prevention in all diabetics above the age of 65 years, or below 65 years if there is at least one additional cardiovascular risk factor present like obesity, hypertension or dyslipoproteinemia. In the case of a known vascular disease proven by the presence of atherosclerotic plaques in the coronary or carotid circulation, or a reduced ABI for the peripheral circulation, all diabetics should be offered a primary prevention with aspirin.