1. Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
2. Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, German Center for Diabetes Research (DZD), 72076 Tübingen, Germany
3. German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
4. Diabetes Center, 1st Propaedeutic Department of Internal Medicine, Medical School, “AHEPA” Hospital, Aristotle University of Thessaloniki, 54621 Thessaloniki, Greece
5. Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic
6. Department of Internal Medicine IV, Division of Endocrinology, Diabetology and Nephrology, University of Tübingen, 72076 Tübingen, Germany