Maternal vitamin D status in gestational diabetes mellitus

Vitamin D deficiency has long been suspected as a risk factor for glucose intolerance. This study compared serum levels of 25-hydroxy vitamin D(3) in pregnant women with gestational diabetes mellitus (GDM), impaired glucose tolerance (IGT), and non-GDM control subjects.

In this case-control study, 54 women with diagnosed GDM and 39 women with IGT (1 abnormal oral glucose tolerance test) were compared with 111 non-GDM control women in whom GDM were excluded by glucose challenge test. Controls were matched in gestational age, age, and body mass index with IGT and GDM groups.

Maternal serum 25-hydroxy vitamin D(3) concentration in GDM and IGT groups at 24-28 weeks of gestation were significantly lower than non-GDM controls (P = .001). A total of 83.3% of GDM compared with 71.2% of the control group had plasma 25-hydroxy vitamin D(3) concentrations consistent with a diagnosis of vitamin D deficiency (<20 ng/mL; P = .03). Women with GDM had a 2.66-fold increased risk of deficient status (25-hydroxy vitamin D(3) <15 ng/mL) compared with control group.

These results suggested that rates of vitamin D deficiency are higher among women with IGT/GDM, and the relationship between vitamin D status and glucose tolerance in pregnancy needs further study.