Abstract

Objective: Diabetic patients may have a higher prevalence of platelet aspirin resistance (AR) than non-diabetic patients. Our goal was to analyze platelet aspirin responsiveness to various aspirin doses in diabetic and non-diabetic patients.

Research Design and Methods: We examined the effect of aspirin (81, 162 and 325mg/day for 4 weeks each) on platelet aspirin responsiveness in 120 stable outpatients (30 diabetic patients, 90 non-diabetic patients) with coronary artery disease (CAD) using light transmittance aggregometry (LTA); VerifyNow; platelet function analyzer (PFA)-100; and levels of urinary 11-dehydro(dh)-thromboxane(Tx)B₂.

Results: In the total group, a low prevalence (0-2%) of AR was observed with all aspirin doses as determined by AA-induced LTA. AR was higher at the 81mg dose in diabetic versus non-diabetic patients using collagen-induced LTA (27% vs. 4%, p=0.001), VerifyNow (13% vs. 3%, p=0.05) and urinary 11dh-TxB₂ (37% vs. 17%, p=0.03). Diabetic patients treated with 81mg exhibited higher platelet function measured by VerifyNow, collagen- and ADP-induced LTA, and 11-dh-TxB₂ levels (p≤ 0.02 for all comparisons). Higher aspirin doses significantly inhibited platelet function and decreased AR in diabetic patients (p<0.05).

Conclusions: Diabetic patients with CAD treated with 81mg aspirin exhibit a higher prevalence of AR and have significantly higher ADP- and collagen-induced platelet aggregation, 11-dh-TxB₂ levels and aspirin reaction units measured by VerifyNow compared to non-diabetic patients. Increased aspirin dosing resulted in similar rates of resistance and platelet function levels between groups. These findings indicate that diabetic patients exhibit a global high platelet reactivity phenotype that may be partially overcome by higher aspirin doses.

Condensed Abstract Diabetic patients may have a higher prevalence of platelet aspirin resistance than non-diabetic patients. Using multiple methods, we analyzed platelet aspirin responsiveness in relation to aspirin dose in 30 diabetic and 90 non-diabetic patients with coronary artery disease. During treatment with 81mg daily aspirin there was a higher prevalence of aspirin resistance and increased platelet function in diabetic patients, however higher aspirin doses resulted in similar rates of resistance and similar platelet function between patient groups (p≤ 0.05). These findings indicate that diabetic patients exhibit a global high platelet reactivity phenotype that may be partially overcome by higher aspirin doses.