[1] UNIV PISA, INST CLIN PHYSIOL, I-56100 PISA, ITALY
[2] UNIV PISA, MED CLIN 2, I-56100 PISA, ITALY
[3] CHU VAUDOIS, DEPT MED, DIV ENDOCRINOL & CLIN BIOCHEM, CH-1011 LAUSANNE, SWITZERLAND
[4] UNIV LAUSANNE, INST PHYSIOL, CH-1000 LAUSANNE 17, SWITZERLAND
[5] UNIV LAUSANNE, LA SOURCE, DIABET UNIT, CH-1000 LAUSANNE 17, SWITZERLAND
[6] YALE UNIV, SCH MED, DEPT MED, NEW HAVEN, CT 06510 USA