Vitamin D concentrations from neonatal dried blood spots and the risk of early-onset type 2 diabetes in the Danish D-tect case-cohort study

Aims/hypothesis The aim of this study was to examine the influence of neonatal vitamin D concentration on the development of early-onset type 2 diabetes in a large population sample. Methods We conducted a case-cohort study utilising data from the Danish biobank and registers. Neonatal vitamin D was assessed measuring 25-hydroxyvitamin D 3 [25(OH)D 3 ] concentrations on the dried blood spot samples from the Biological Specimen Bank for Neonatal Screening. Cases of type 2 diabetes ( n = 731) were retrieved from the Danish National Patient Register for all individuals born in Denmark between 1 May 1981 and 31 December 1992. The sub-cohort ( n = 1765) was randomly selected from all children born in the same period. We used a weighted Cox proportional hazard model assessing the hazard of first type 2 diabetes diagnoses by quintiles of 25(OH)D 3 and restricted cubic spline. Results The median 25(OH)D 3 concentration (IQR) among cases was 21.3 nmol/l (13.3–34.1) and 23.9 nmol/l (13.7–35.7) in the sub-cohort. There was no indication of a potential lower risk of early-onset type 2 diabetes among individuals in the higher quintile of vitamin D concentration compared with the lowest (HR crude 0.97 [95% CI 0.71, 1.33] p = 0.85; HR adjusted 1.29 [95% CI 0.92, 1.83] p = 0.14). Conclusions/interpretation The results of this study do not support the hypothesis that higher neonatal vitamin D concentrations are associated with a lower risk of early-onset type 2 diabetes in adulthood. Graphical abstract