Atherosclerosis and platelet activity are two important chain factors linked together in the onset and the severity of coronary artery disease. Our study included 60 diabetic patients with ischemic heart disease, all having underwent coronary angiography. In this substudy from a larger epigenetical and genetical study, we phocused on the interrelationship between vessel disease and primary hemostasis. The haematological parameters included were platelet count (PLT), the platelet distribution width (PDW), the mean platelet volume (MPV) and the platelet larger cell ratio (P-LCR). ). The severity of the coronary disease was defined by the number of stenotic/occluded coronary arteries. We demonstrated a positive corelation with the duration of diabetes (p=0.032), as 34% of the patients with a long duration of the diabetes had a higher number of platelets. The mean platelet volume was slightly elevated in diabetic females over 65 years old, compared to younger diabetic men, though not statistically significant (p=0.101). Although the investigated parameters were mostly in the normal range, the fact that for some cathegories of patients they were orientated towards the upper limit, raises some questions for the next studies. Future adjustments of lot number and selection criteria for the following studies are needed. Using the MPV as a prediction test for cardiovascular complications is still a controversial subject, since the scientifical background contains both positive and negative studies on this matter.