Dual antiplatelet therapy is essential in patients following ST-Elevation myocardial infarction (STEMI) with percutaneous coronary intervention (PCI) and drug eluting stent implantation. Current guidelines recommend prasugrel and ticagrelor in patients with STEMI undergoing primary PPCI. We sought to investigate the superiority antiplatelet effect in terms of PR level of loading dose (LD) of Prasugrel (60 mg) versus LD of Ticagrelor (180 mg) in diabetic patients with STEMI undergoing primary PCI at 1 and 2 hours post drug administration. Secondary end-points will be: PR level measured at 6 and 12 hours post study drugs administrationin hospital. All consecutive diabetic patients with STEMI undergoing PPCI with stent implantation will be considered for PR assessment at 1-2-6-12 h after the drug LD administration. All patients must will be naïve for platelet P2Y12 receptor inhibition therapy. A subanalysis will be performed between two study groups according to insulin treatment.