1. Department of Public Health, Faculty of Medicine, Heinrich-Heine University Düsseldorf, Germany
2. German Diabetes Center, Institute of Biometrics and Epidemiology, Düsseldorf, Germany
3. Clinic for Paediatrics, Evangelisches Krankenhaus Oberhausen, Germany
4. Institute of Epidemiology and Medical Biometry, Faculty of Medicine, University of Ulm, Ulm, Germany