1. Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), CH-8091 Zurich, Switzerland
2. Department of Medicine IV, University Hospital, LMU Munich, 80336 Munich, Germany
3. Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Carl Gustav Carus, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
4. Department of Medicine III, University Hospital Carl Gustav Carus, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
5. Department of Nuclear Medicine, La Timone University Hospital, CERIMED, Aix-Marseille University, 13273 Marseille, France
6. Department of Medicine, Division of Endocrinology and Diabetes, University Hospital, University of Würzburg, 97080 Würzburg, Germany
7. Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX2 6HG, UK
8. Centre for Endocrinology, Barts and the London School of Medicine, London EC1M 6BQ, UK
9. ENETS Centre of Excellence, Royal Free Hospital, London NW3 2QG, UK
10. Section on Medical Neuroendocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20847, USA