Department of Vascular Medicine (L.F.R., G.K.H.), Amsterdam UMC, location AMC, University of Amsterdam, The Netherlands. Institute for Diabetes, Obesity, and Metabolism (J.S.M.), Perelman School of Medicine, University of Pennsylvania, Philadelphia. Division of Translational Medicine and Human Genetics, Department of Medicine (J.S.M., L.W., D.J.R., M.C.), Perelman School of Medicine, University of Pennsylvania, Philadelphia. Department of Experimental Vascular Medicine (H.J.), Amsterdam UMC, location AMC, University of Amsterdam, The Netherlands. Stable Isotope Research Laboratory, Endocrinology, Vrije Universiteit (D.v.H., H.S.), Amsterdam UMC, location AMC, University of Amsterdam, The Netherlands. Regeneron Pharmaceuticals, Inc, Tarrytown, NY (D.A.G.).