1. Division of Diabetes and Metabolism, The Institute of Medical Science, Asahi Life Foundation, 2-2-6, Nihonbashi Bakurocho, Chuo-ku, Tokyo 103-0002, Japan
2. Department of Endocrinology and Diabetes, Saitama Medical University, 38 Morohongo Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
3. Department of Diabetes, Metabolism and Endocrinology, Ichikawa Hospital, International University of Health and Welfare, 6-1-14 Kounodai, Ichikawa City, Chiba 272-0827, Japan
4. Department of Pharmacotherapy, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose City, Tokyo 204-8588, Japan