1. Department of Medicine III, Division of Endocrinology, Nephrology and Rheumatology, University of Leipzig, Liebigstr. 18, 04103 Leipzig, Germany
2. Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG), Helmholtz Center Munich at the University of Leipzig and the University of Leipzig Medical Center, 04103 Leipzig, Germany
3. German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany