1. Department of Endocrinology and Diabetology, Medical Faculty and University Hospital, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
2. Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
3. German Center for Diabetes Research, Partner Düsseldorf, München-Neuherberg, Germany.
4. Institute for Clinical Biochemistry and Pathobiochemistry German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
5. Institute for Biometrics and Epidemiology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
6. Division of Endocrinology, Diabetes and Nutrition, Mayo Clinic, Rochester, MN, USA.
7. Institute of Biochemistry and Molecular Biology I, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
8. Department of Internal Medicine, Heidelberg University, Heidelberg, Germany.