||Objective: The purpose of this study was to assess platelet aggregation (PA) in the diabetic and in non-diabetic patients, also, to determine the impact of anthropometric, demographic factors and concomitant drug use on the PA in the presented groups of the patients. Methods: The study sample consisted of the (n=286) patients who were hospitalized due to ACS and were prescribed DAPT (aspirin and clopidogrel) at the Department of Cardiology of the hospital of LUHS Kauno Klinikos. Patients followed DAPT for at least 2 weeks from hospitalization. PA was assessed by using light transmittance aggregometry. Adenosine diphosphate (ADP), epinephrine (ADR), and arachidonic acid (ARA) were used to induce PA. The results were presented as the mean ± standard deviation (SD). The results were considered as statistically significant when p≤0.05. Results: PA induced by ADP (26.12 ± 7.76 %agr vs. 35.57 ± 14.11 %agr) and ADR (29.67 ± 12.73 %agr vs. 35.99 ± 17.08 %agr) was significantly higher in the diabetic patients. PA with ARA levels did not differ significantly in the presented patient groups. Significantly lower PA values were determined in the non-diabetic patients vs diabetic patients: younger than 60 years old (26.71 ± 8.01 %agr vs. 33.05 ± 13.72 %agr), older than 60 years of age (25.69 ± 7.58 %agr vs. 36.38 ± 14.25 %agr), males (25.47 ± 7.93 %agr vs. 35.12 ± 14.41 %agr) and females (28.02 ± 7.00 %agr vs. 36.45 ± 13.72 %agr), in the patients, according to their waist circumference (<90 cm: 25.70 ± 6.89 %agr vs. 34.10 ± 16.25 %agr, 90-99 cm: 25.68 ± 7.61%agr vs. 35.75 ± 12.88 %agr and >99 cm: 26.94 ± 8.71 %agr vs. 35.77 ± 14.38 %agr. PA was significantly higher in the diabetic patients compared to nondiabetic patients, regardless to the concomitant drug usage: ACE inhibitors, aspirin, furosemide/torasemide, ISMN, ivabradine, ranitidine, spironolactone or statins. Conclusions: DAPT with aspirin and clopidogrel was less effective in the diabetic patients’ sample. Diabetic patients had significantly higher PA levels than compared to the non-diabetic patients despite their age, gender, waist circumference or concomitant drug usage.