1. Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
2. German Center for Diabetes Research, Munich-Neuherberg, Neuherberg, Partner Düsseldorf, Düsseldorf, Germany
3. Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
4. Second Department of Internal Medicine, Diabetes Center, Diabetic Foot Clinic, Democritus University of Thrace, Alexandroupolis, Greece
5. Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany