1. Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, China
2. Beijing Municipal Key Laboratory of Clinical Epidemiology, Beijing, China
3. Department of Endocrinology, Chinese PLA General Hospital, Beijing, China
4. Department of Endocrinology, Hainan Branch of Chinese PLA General Hospital, Sanya, China
5. Departments of Medicine and Physiology, University of Toronto, Toronto, Onatario, Canada