Impact of diabetes mellitus and metabolic syndrome on acute and chronic on-clopidogrel platelet reactivity in patients with stable coronary artery disease undergoing drug-eluting stent placement

Background Previous studies, which compared the prevalence of high on-clopidogrel platelet reactivity (HCPR) in type 2 diabetes mellitus (T2DM) versus non-T2DM and obese versus nonobese patients provided conflicting results. Methods We compared the prevalence of HCPR in patients with T2DM, metabolic syndrome (MS), or neither T2DM nor MS undergoing drug-eluting stent implantation for stable coronary artery disease. Platelet functions were measured after a 600-mg clopidogrel loading dose and after 4 months on clopidogrel 75 mg/d. Results The prevalence of HCPR was significantly higher in 63 T2DM and 50 MS patients than in 43 patients with neither T2DM nor MS (46.0% and 52.0% vs 20.9%) after clopidogrel loading dose, whereas, at 4 months, only T2DM patients had a significantly higher prevalence of HCPR (50.8% and 31.3% vs 23.8%). By multivariable analysis, T2DM (odds ratio [OR] 3.62, 95% CI, 1.34-9.80, P = .011), MS (OR 4.00, 95% CI 1.39-11.46, P = .010), and previous chronic treatment with clopidogrel (OR 0.22, 95% CI 0.09-0.49; P < .001) were the main independent predictors of HCPR after clopidogrel loading dose, whereas only T2DM (OR 2.98, 95% CI 1.20-7.41, P = .017) was an important independent predictor of HCPR at 4 months. Conclusions Both MS and T2DM were independent predictors of HCPR after clopidogrel loading dose. On clopidogrel maintenance therapy, only T2DM remained an independent predictor. This observation may be clinically relevant in the current era of antiplatelet therapy.