Background. The relationships between vitamin D[25(OH)D] deficiency and gestational diabetes mellitus(GDM) are under investigation. We wanted to assessthe relationships between maternal 25(OH)D concentrationand metabolic indicators, and blood pressurein women with GDM.

Methods. Prospective study was conducted in northernPoland between September 2012 and February2013. GDM was diagnosed by 75 g OGTT between 20––29 weeks of pregnancy. Pre-gestational BMI werecalculated, weight gain during pregnancy and bloodpressure were collected. Fasting glucose, insulin, lipids,25(OH)D were assessed. HOMA-IR was used to estimateinsulin resistance, defined as > 2.5. The women were dividedinto group A with 25(OH)D deficiency (≤ 20 ng/mL)and group B with 25(OH)D > 20 ng/mL. Statisticalanalysis was performed.

Results. We analyzed 56 pregnant women with GDM,mean age 30.3 ± 5.1. 25(OH)D deficiency was found in25 women (44.6%) with its concentration 13.8 ± 3.9ng/mL. In the group B, the mean 25(OH)D concentrationwas 30.6 ± 9.3 ng/mL. 25(OH)D deficiency wasassociated with higher systolic blood pressure (p == 0.03), insulin resistance (p = 0.38) and with thethird and subsequent pregnancies (p = 0.047). 25(OH)D concentration was 22.8 ± 2.0 ng/mL in the first andsecond pregnancies, comparing to 14.3 ± 3.9 ng/mL inthe third and subsequent pregnancies. There was nocorrelation between 25(OH)D and other parameters.

Conclusions. 1. Low 25(OH)D concentration in theanalyzed group of women with GDM was significantlycorrelated with increased insulin resistance and systolicblood pressure. 2. In multipara the incidence of 25(OH)Ddeficiency was higher. 3. The results imply necessity offocusing on guidelines implementation for 25(OH)Dsupplementation for women in childbearing age.