1. Isala, Diabetes Centre, Zwolle, Netherlands
2. Isala, Department of Internal Medicine, Zwolle, Netherlands
3. Gelre Hospital, Department of Internal Medicine, Apeldoorn, Netherlands
4. Langerhans Medical Research Group, Zwolle, Netherlands
5. University of Groningen, University Medical Center Groningen, Department of General Practice, Groningen, Netherlands
6. University of Groningen, University Medical Center Groningen, Department of Internal Medicine, Groningen, Netherlands