1. Department of Medicine; University of Groningen; University Medical Center Groningen; Groningen the Netherlands
2. Department of Gastroenterology; Isala Clinics; Zwolle the Netherlands
3. Department of Medicine; Gelre Hospital; Apeldoorn the Netherlands
4. Diabetes Centre; Isala Clinics; Zwolle the Netherlands
5. Department of General Practice; University of Groningen; University Medical Center Groningen; Groningen the Netherlands
6. Department of Laboratory Medicine; University Medical Center Groningen; Groningen the Netherlands
7. Langerhans Medical Research Group; Zwolle the Netherlands