1. Division of Endocrinology and Metabolism, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul 03312 , Republic of Korea
2. Division of Endocrinology and Metabolism, Department of Internal Medicine, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul 07345 , Republic of Korea
3. Division of Endocrinology and Metabolism, Department of Internal Medicine, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Uijeongbu 11765 , Republic of Korea
4. Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul 06591 , Republic of Korea
5. Division of General Internal Medicine, Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam 13620 , Republic of Korea