Norbert Stefan1, Andreas Peter2, Hans-Ulrich Häring2. 1. Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; and German Center for Diabetes Research, Tübingen, Germany norbert.stefan@med.uni-tuebingen.de. 2. Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University Hospital Tübingen, Tübingen, Germany; Institute of Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; and German Center for Diabetes Research, Tübingen, Germany.