[1] Orebro Univ Hosp, Dept Pediat, S-70185 Orebro, Sweden
[2] Karolinska Univ Hosp, Karolinska Inst, Dept Med, Clin Epidemiol Unit, Stockholm, Sweden
[3] Linkoping Univ, Fac Hlth Sci, Dept Mol & Clin Med, Div Pediat, Linkoping, Sweden
[4] Linkoping Univ, Fac Hlth Sci, Dept Mol & Clin Med, Ctr Diabet Res, Linkoping, Sweden
[5] Harvard Univ, Sch Med, Cambridge, MA 02138 USA
[6] Orebro Univ Hosp, Clin Res Ctr, Orebro, Sweden