1. German Diabetes Center, Institute for Clinical Diabetes Research, Düsseldorf, Germany.
2. West German Diabetes and Health Center, Düsseldorf, Germany.
3. Medical University Hannover, Institute for Biometry, Hannover, Germany.
4. Profil Institute for Metabolic Research, Neuss, Germany.
5. Institute for Medical Informatics and Biostatistics, Basel, Switzerland.
6. Department of Endocrinology, Diabetes and Rheumatology, University of Düsseldorf, Düsseldorf, Germany.