1. Division of Endocrinology and Metabolism, Inha University Hospital, Inha University School of Medicine, Incheon, Korea.
2. Division of Endocrinology and Metabolism, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Division of Clinical Epidemiology and Biostatics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Division of Endocrinology and Metabolism, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
5. Division of Endocrinology and Metabolism, Dong-A University Medical Center, Dong-A University College of Medicine, Busan, Korea.
6. Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
7. Division of Endocrinology and Metabolism, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.