1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Institute of Endocrinology, Goodmorning Hospital, Pyeongtaek, Korea.
3. Institute of Endocrinology, Gwangmyung Sungae Hospital, Gwangmyeong, Korea.
4. Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.
5. Diabetes Center, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.