1. CNR Institute of Neuroscience, Padua, Italy;
2. Department of Internal Medicine, University of Pisa School of Medicine, Pisa, Italy;
3. CNR Institute of Clinical Physiology, Pisa, Italy;
4. Hanusch Hospital, Vienna, Austria;
5. Heinrich-Heine University, Düsseldorf, Germany;
6. German Diabetes Center, Düsseldorf, Germany; and
7. German Center of Diabetes Research, München-Neuherberg, Germany