This will be a single-center, randomized, open-label, active-controlled, parallel-group study to investigate the platelet inhibition of Ticagrelor versus Clopidogrel with acetylsalicylic acid (ASA) as background therapy in approximate 40 patients with stable coronary artery disease (SCAD) and type 2 diabetes mellitus (DM) after recent successful elective percutaneous coronary intervention (PCI) by evaluation of the P2Y12 reaction unit (PRU) by VerifyNow P2Y12 assay at 2-4 hours after the first study drug dose on treatment day 15±2.