1. Institute of Diabetes Research and Metabolic Diseases, Helmholtz Center Munich German Research Center for Environmental Health, 72076 Tübingen , Germany
2. German Center for Diabetes Research , 85746 Neuherberg , Germany
3. Department for Diabetology, Endocrinology, and Nephrology, Faculty of Medicine, Eberhard Karls University Tübingen , 72076 Tübingen , Germany
4. Medical Department III—Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center , 04103 Leipzig , Germany
5. Department of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, University Hospital , 40225 Düsseldorf , Germany
6. Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University , 40225 Düsseldorf , Germany
7. Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital Tübingen , 72076 Tübingen , Germany
8. Division of Endocrinology and Diabetology, Department of Internal Medicine 1, University Hospital Ulm , 89070 Ulm , Germany