Evaluation of platelet reactivity during combined antiplatelet therapy in patients with stable coronary artery disease in relation to diabetes type 2 and the GPIIB/IIIA receptor gene polymorphism.

Antiplatelet therapy resistance against acetylsalicylic acid (ASA) and/or clopidogrel in coronary heart disease (CHD) is common with diabetes mellitus. One factor might involve platelet receptor ITGB3 gene polymorphism. We aimed to assess resistance together with platelet reactivity parameters, the polymorphism, plus diabetes type 2 coexistence. The study included 185 patients with CHD, including 58 diabetics, aged 62.3 ± 8.2 years. Patients were treated long-term with ASA, plus clopidogrel, both 75 mg/d. Platelet aggregation was measured with arachidonic acid (ASPI test; ASA-response assessment) or ADP (ADP test; clopidogrel-response assessment). Thromboxane B2 (TXB2) and fibrinogen concentrations were measured and ITGB3 PIA1>A2 variants identified. Increases in PLT, glucose and SBP were demonstrated with dual resistance or to clopidogrel. Regardless of response, diabetics (versus non-diabetics) had elevated platelet aggregation with the ADP test (P = 0.0198), higher TXB2 (P = 0.0501), BMI (P = 0.0003) and SBP (P = 0.0627). ITGB3 PIA1/A1 homozygotes had higher platelet aggregation with the ASPI test (P = 0.0513), and fibrinogen concentrations (P = 0.0133), relative to A2 allele carriers. Significant associations of diabetes with clopidogrel resistance (P = 0.0011) and PIA1/A1 homozygotes with ASA resistance (P = 0.0518) were found. Higher concentrations of TXB2 (P = 0.0223) and higher SBP (P = 0.0063) were found with diabetes (versus non-diabetic) in PIA1/A1 homozygotes. We concluded that diabetes with CHD weakens response to antiplatelet drugs, especially to clopidogrel; and hyperglycaemia, hypertension and obesity might also play an important role. Diabetics' resistance to ASA is associated with increased platelet reactivity, perhaps related to the more frequent ITGB3 PIA1 allele and increased TXB2 generation. The PIA1 allele may be a potential factor for aspirin resistance with elevated fibrinogen concentration.