1. Unit of Endocrinology, Scientific Institute Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
2. Unit of Diabetes, Ospedali Riuniti of Bergamo, Bergamo, Italy
3. Chair of Metabolic Diseases, University of Padova, Padova, Italy
4. Unit of Clinical Chemistry, Scientific Institute Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
5. Department of Medical and Surgical Sciences, University of Padova, Padova, Italy
6. Department of Clinical Sciences, University La Sapienza, Rome, Italy