1. Institute for Biometrics and Epidemiology; German Diabetes Centre; Leibniz Centre for Diabetes Research at Heinrich Heine University Düsseldorf; Düsseldorf Germany
2. German Centre for Diabetes Research; München-Neuherberg Germany
3. Paul Langerhans Group for Health Services Research and Health Economics; German Diabetes Centre; Leibniz Centre for Diabetes Research at Heinrich Heine University Düsseldorf; Düsseldorf Germany
4. Institute for Health Service Research and Health Economics; Centre for Health and Society; Medical Faculty; Heinrich-Heine-University Düsseldorf; Düsseldorf Germany