Effects of Agonists of Glucagon Like Peptide - 1 Receptors (GLP-1R) on Arterial Stiffness, Endothelial Glycocalyx and Coronary Flow Reserve in Patients With Coronary Artery Disease and Patients With Diabetes Mellitus

The investigators will study three groups matched for age and sex: 30 patients with type 2 diabetes mellitus (T2DM) without coronary artery disease (CAD), 30 patients with T2DM and CAD and 30 obese patients (BMI \>30 Kg/m²) with abnormal oral glucose tolerance test (OGTT). It will be a randomized study with metformin or GLP-1R agonist treatment for 1 year. All subjects will receive for 1 year: (a) GLP-1R agonist or (b) metformin. At 0, 3, 6 and 12 months, where 0 is the starting point of treatment, blood samples will be collected. At 0, 3, 6 and 12 months the investigators will measure: 1. Carotid-femoral pulse wave velocity (PWV, m/sec) using tonometry by Complior (SP ALAM) and augmentation index (AI, %) by the method of arteriography (Arteriograph, TensioMed) 2. Perfused boundary region (PBR, micrometers) of the sublingual arterial microvessels (ranged from 5-25 micrometers) using Sideview Darkfield imaging (Microscan, Glycocheck). Increased PBR is considered an accurate non invasive index of reduced endothelial glucocalyx thickness. 3. Coronary flow reserve (CFR) in the left anterior descending artery after infusion of adenosine using Doppler echocardiography. 4. Determination of the following parameters in blood: glucose, insulin, free fatty acids, triglycerides, glycerol, C reactive protein (CRP), transforming growth factor-b (TGF-b), Lipoprotein-Associated Phospholipase A2 (LP-LPA2), tumor necrosis factor-a (TNF-a), interleukins 6 and 10 (IL6 and IL10), propeptide of type I procollagen (PIP), propeptide of procollagen type III (PIIINP), matrix metallopeptidases 9 and 2 (MMP), macrophage-colony stimulating factor (MCSF), growth differentiation factor-15 (GDF-15), N-terminal pro b-type natriuretic peptide (NT-proBNP) and galectin-3.