1. Service de diabétologie, Centre Hospitalier de Nevers, F-58320 Pougues-les-Eaux, France.
2. Hôpital de la Conception, F-13385 Marseille Cedex 4, France.
3. Reims University Hospital, F-51100 Reims, France.
4. Department of Clinical Vitaminology, F. Hoffmann-La Roche, CH-4002, Basle, Switzerland.