**At baseline and 6 month follow-up, participants will undergo non-invasive testing of endothelial cell function using the Endothelial Peripheral Arterial Tone (EndoPAT). The EndoPAT is a medical device based on noninvasive Peripheral Arterial Tone (PAT)signal technology. It measures endothelium-mediated changes in vascular tone using unique bio-sensors placed on the fingertips. These changes in arterial tone are elicited by creating a down-stream hyperemic response induced by a standard 5-minute occlusion of the feeding artery (using a standard blood pressure cuff). When the cuff is released, the surge of blood flow causes an endothelium-dependent Flow-Mediated Dilation (FMD). The dilation or reactive hyperemia is captured by EndoPAT as an increase in the PAT Signal amplitude. A post-occlusion to pre-occlusion ratio is automatically calculated by the EndoPAT software, thus providing the EndoScore. Measurements from the opposite arm are used to control for concurrent non-endothelial dependent changes in vascular tone. Participants will be asked to clip their index fingernails before the visit or a research assistant may clip their fingernails before the study using sterilized clippers. Fingernails may need to be clipped if they are too long for the probes.