Despite treatment with aspirin a large number of patients suffer a myocardial infarction. It has been speculated that these patients might be "resistant" to aspirin, and studies have indicated that this phenomenon is related to a less favourable prognosis. Furthermore, patients with diabetes mellitus have an increased risk of myocardial infarction and other vascular events and, recently, it has been suggested that diabetics do not respond adequately to aspirin. The purpose of this study is to compare the prevalence of "aspirin resistance" in diabetics and non-diabetics. Furthermore, patients who suffered a myocardial infarction while being treated with aspirin are included. We hypothesize that the prevalence of "aspirin resistance" will be higher among diabetics compared to other patients and to healthy individuals.

A considerable number of patients suffer acute coronary events despite being treated with antiplatelet therapy such as aspirin. Taken together with laboratory findings of a low response to aspirin, the term "aspirin resistance" has been coined. Diabetics have an increased risk of suffering ischemic vascular events and, recently, an increased prevalence of "aspirin resistance" was reported in these patients. The purpose of the present study is to compare the aspirin response in diabetics and non-diabetics in a population with angiogram-verified coronary artery disease. Furthermore, healthy volunteers and patients who suffered a myocardial infarction while being treated with aspirin are included. Eligible patients are identified in the Western Denmark Heart Registry.

Inclusion Criteria:

• Ischemic heart disease verified by coronary angiogram (group:"CAD")
• treatment with aspirin 75 mg/d for at least the previous 7 days(groups: "CAD" and "Previous myocardial infarction")
• type II diabetes mellitus (~50% of groups: "CAD" and "Previous myocardial infarction")
• ≥ 1 myocardial infarction more than one year ago while taking daily aspirin ≥ 75 mg/d (group: "Previous myocardial infarction").

Exclusion Criteria:

• treatment with NSAIDs, clopidogrel, ticlopidine, dipyridamole, warfarin or any other drugs known to affect platelet function.
• ischemic vascular event within the previous 12 months
• revascularization (angioplasty or coronary by-pass graft surgery) within the previous 12 months
• intake of NSAIDs within 1 week of myocardial infarction (group: "Previous myocardial infarction").
• platelet count < 120 x 10^9/l
• previous myocardial infarction (group: "CAD").
• not able to give informed consent