[1] Telemark Hosp, Dept Paediat & Adolescent Med, Skien, Norway
[2] Oslo Univ Hosp, Norwegian Childhood Diabet Registry, Oslo, Norway
[3] Norwegian Inst Publ Hlth, Dept Res & Anal Hlth Serv, Div Hlth Serv, Oslo, Norway
[4] Oslo Univ Hosp, Oslo Ctr Biostat & Epidemiol, Res Support Serv, Oslo, Norway
[5] Oslo Univ Hosp, Div Paediat & Adolescent Med, Oslo, Norway
[6] Univ Oslo, Inst Clin Med, Fac Med, Oslo, Norway
[7] Oslo Univ Hosp, Oslo Diabet Res Ctr, Oslo, Norway
[8] Telemark Hosp, Dept Paediat & Adolescent Med, N-3710 Skien, Norway