1. Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University College of Medicine , 73, Goryeodae-ro, Seongbuk-gu, Seoul 02841 , Republic of Korea
2. Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81, Irwon-ro, Gangnam-gu , Seoul 06351 , Republic of Korea