title: Neonatal vitamin D status is not associated with later risk of type 1 diabetes: results from two large Danish population-based studies.
abstract: The aim of this work was to assess whether neonatal levels of 25-hydroxyvitamin D (25(OH)D) are associated with risk of developing type 1 diabetes before the age of 18 years.
  
  
  
  Two large-scale studies with different designs-a case-cohort and a case-control-were conducted using Danish national register data and biobank material. Weighted Cox regression and conditional logistic regression were used to calculate HRs and ORs, respectively. The concentration of 25(OH)D was assessed from neonatal dried blood spots using highly sensitive liquid chromatography-tandem mass spectrometry. Quintiles of 25(OH)D3 were used in the main analyses.
  
  
  
  The case-cohort study included 912 type 1 diabetes cases and 2866 individuals without type 1 diabetes born in Denmark between 1981 and 2002 and followed up until the end of 2012. The case-control study included 527 matched case-control pairs born between 1981 and 1999 and followed up until May 2004. Both studies found no association between 25(OH)D3 levels and later risk of developing type 1 diabetes. The neonatal total 25(OH)D levels in the studies were low: 46% (case-cohort study) and 51% (case-control study) of individuals had 25(OH)D levels <25 nmol/l.
  
  
  
  Our two large-scale national studies showed that 25(OH)D3 levels around the time of birth were not associated with later type 1 diabetes risk. Whether higher levels of 25(OH)D3 during pregnancy, acquired by higher doses of supplementation than are recommended today in most countries, could protect the offspring against type 1 diabetes cannot be ruled out by the present studies.
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, Copenhagen University Hospital, Bispebjerg og Frederiksberg, Nordre Fasanvej 57, Hovedvejen, Entrance 5, Ground Floor, 2000, Frederiksberg, Denmark. ramune.jacobsen@regionh.dk.|The Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, The Capital Region, Frederiksberg, Denmark. ramune.jacobsen@regionh.dk.
authors.forename: Ramune
authors.initials: R
authors.lastname: Jacobsen
authors.affiliation: Copenhagen Diabetes Research Center (CPH-DIRECT), Department of Paediatrics, Herlev Hospital, University of Copenhagen, Herlev, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Steffen U
authors.initials: SU
authors.lastname: Thorsen
authors.affiliation: Department of Congenital Disorders, Statens Serum Institute, Copenhagen, Denmark.
authors.forename: Arieh S
authors.initials: AS
authors.lastname: Cohen
authors.affiliation: Department of Congenital Disorders, Statens Serum Institute, Copenhagen, Denmark.
authors.forename: Marika
authors.initials: M
authors.lastname: Lundqvist
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, Copenhagen University Hospital, Bispebjerg og Frederiksberg, Nordre Fasanvej 57, Hovedvejen, Entrance 5, Ground Floor, 2000, Frederiksberg, Denmark.
authors.forename: Peder
authors.initials: P
authors.lastname: Frederiksen
authors.affiliation: Department of Public Health, Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Pipper
authors.affiliation: Copenhagen Diabetes Research Center (CPH-DIRECT), Department of Paediatrics, Herlev Hospital, University of Copenhagen, Herlev, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Pociot
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.
authors.forename: Lau C
authors.initials: LC
authors.lastname: Thygesen
authors.affiliation: Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ascherio
authors.affiliation: Copenhagen Diabetes Research Center (CPH-DIRECT), Department of Paediatrics, Herlev Hospital, University of Copenhagen, Herlev, Denmark.|Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jannet
authors.initials: J
authors.lastname: Svensson
authors.affiliation: Research Unit for Dietary Studies at The Parker Institute, Copenhagen University Hospital, Bispebjerg og Frederiksberg, Nordre Fasanvej 57, Hovedvejen, Entrance 5, Ground Floor, 2000, Frederiksberg, Denmark.|The Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, The Capital Region, Frederiksberg, Denmark.|National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.|The Boden Institute of Obesity, Nutrition Exercise and Eating Disorders, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.|Institute of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Berit L
authors.initials: BL
authors.lastname: Heitmann
mesh_terms: D016022:Case-Control Studies; D002853:Chromatography, Liquid; D003718:Denmark; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D016016:Proportional Hazards Models; D012042:Registries; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D
keywords: Denmark; Gestation; Registers; Type 1 diabetes; Vitamin D