Following an overnight fast (12 hours), subjects will come in the morning to our Adult Translational Research Unit (A-TRU) which is part of the Clinical Translational Research Initiative of Southeast Wisconsin (8UL1TR000055). An antecubital intravenous line will be placed to facilitate blood glucose sampling during the hyperglycemic challenge. An antecubital intravenous catheter will be placed to facilitate obtaining endothelial cells from the vein by J-wire biopsy for of mitochondrial testing. The principal investigator has published experience with the J-wire endothelial cell biopsy technique, and the technique has been extensively validated technique. An initial venous glucose sample will be taken from the antecubital vein and an initial J-wire biopsy of the radial artery endothelium will be performed through the radial arterial line. Subjects will then be asked to drink a standardized 75 g glucose drink created by the A-TRU nutritionist- a standard oral glucose challenge as used clinically. Blood glucose samples will be taken hourly after that until 4 hours post drink ingestion. At one and 4 hours post-ingestion, J-wire endothelial biopsies of the radial artery will be repeated. Four separate J wires will be passed into the radial artery for each measurement time point (0,1, and 4 hours).