[1] The University of Auckland,Section of Epidemiology and Biostatistics, School of Population Health
[2] University of Oslo,Institute of General Practice and Community Medicine, Section for Preventive Medicine and Epidemiology
[3] Norwegian Institute of Public Health,Division of Epidemiology
[4] Aker University Hospital,Centre of Endocrinology
[5] University of Oslo,Faculty of Medicine
[6] University of Oslo,Institute of General Practice and Community Medicine