1. Third Department of Internal Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
2. Kasukabe Municipal Hospital, Saitama 344-8588, Japan
3. Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd., Tsukuba 300-2611, Japan
4. Department of Endocrinology and Metabolism, Institute for Adult Diseases, Asahi Life Foundation, Tokyo 103-0002, Japan