Vitamin D levels at birth and risk of type 1 diabetes in childhood: a case-control study

To assess whether vitamin D levels at birth were associated with risk of having type 1 diabetes up to 10 years of age and the potential modifier effect of ethnic group. The Piedmont Diabetes Registry and the Newborn Screening Regional data were linked to identify cases (n = 67 incident children aged a parts per thousand currency sign10 years at diabetes onset, 2002-2012) and up to five controls (n = 236) matched for birthday and ethnic group. Cards with neonatal blood spot were used and 25-hydroxyvitamin D(3) assessed with tandem mass spectroscopy. In conditional logistic regression, OR for unit increment of log vitamin D was 0.78 (95 % CI 0.56-1.10). Vitamin D was significantly lower in migrant than in Italian control newborn babies (p < 0.0001), and interaction between vitamin D and migrant status was statistically significant (p = 0.04). Compared to migrant newborns babies with vitamin D a parts per thousand yen 2.14 ng/ml, migrants with lower levels had an OR of 14.02 (1.76-111.70), whereas no association was evident in Italians. Our case-control study within the Piedmont Diabetes Registry showed no association between vitamin D levels at birth and risk of having type 1 diabetes up to 10 years of age, apart from the subgroup of migrant babies, which might have clinical implications if confirmed.