1. Department of Diabetes and Endocrinology, Saiseikai Yokohamashi Nanbu Hospital, Yokohama 234-0054, Japan
2. Department of Internal Medicine, Division of Metabolism and Endocrinology, Yokohama Sakae Kyosai Hospital, Federation of National Public Service Personnel Mutual Associations, Yokohama 247-0005, Japan
3. Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan