1 Diabetes Centre, Isala, Dr Spanjaardweg 11, Zwolle, 8025 BT, the Netherlands
2 Innofeet Voetencentrum Nijenhuis Podiatry, Simon Stevinweg 13, Zwolle, 8013 NA, the Netherlands
3 Department of Internal Medicine, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9700 RB, the Netherlands
4 Langerhans Medical Research Group, Postbus 21, Sleeuwijk, 4254 ZG, the Netherlands
5 Department of Medical Microbiology, Isala, Zwolle, 8025 AB, Dr. van Heesweg 2, the Netherlands
6 Department of General Practice, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9700 RB, the Netherlands
7 Department of Internal Medicine, Gelre Hospital, Albert Schweitzerlaan 31, Apeldoorn, 7334 DZ, the Netherlands