 The primary endpoint is the change in mean flow velocity in the middle cerebral arteries measured by transcranial doppler. The secondary endpoints are the effects on the peripheral endothelium, hereby: 1 changes in the reactive hyperaemia index measured by EndoPAT2000, 2 changes in the ankle-brachial index, and 3 changes in endothelialinflammatory biomarkers in the blood. The primary and secondary endpoints are measured before and up till three hours after administration of exenatide. 