1 Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea. limsoo@snu.ac.kr.
2 Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, South Korea.
3 Department of Internal Medicine, Yeouido St. Mary's Hospital, The Catholic University of Korea, Seoul, South Korea.
4 Diabetes Division, Katholisches Klinikum Bochum, St Josef- Hospital (Ruhr- Universität Bochum), Bochum, Germany.