1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Graduate School, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Endocrinology and Metabolism, Inha University School of Medicine, Incheon, Korea.
4. Huh's Diabetes Center and the 21st Century Diabetes and Vascular Research Institute, Seoul, Korea.
5. Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Korea.