1. Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine , Seoul 05278 , Korea
2. Department of Internal Medicine, Ulsan University Hospital, College of Medicine, Ulsan University , Ulsan 44033 , Korea
3. Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul 06351 , Korea
4. Department of Health Promotion Center, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul 06351 , Korea
5. Department of Clinical Research Design & Evaluation, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University , Seoul 06351 , Korea