1Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Tübingen, Germany, 2Department of Endocrinology, Metabolism, Clinical Chemistry, Nephrology and Angiology, University Hospital of Tübingen, Tübingen, Germany, 3Department of Diagnostic and Interventional Radiology, Section on Experimental Radiology, University Hospital of Tübingen, Tübingen, Germany, 4Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen (Paul Langerhans Institute Tübingen), Tübingen, Germany, 5German Center for Diabetes Research (DZD), Tübingen, Germany