Endocrine Abstracts

Introduction: The results of publications investigating the relationship between low maternal serum 25-hydroxyvitamin D (25OHD) level and gestational diabetes mellitus (GDM) are controversial and none of these publications have investigated this relationship according to the severity of 25OHD deficiency. Therefore, this study was conducted to assess the relationship between low maternal serum 25OHD and GDM according to the severity of 25OHD deficiency.

Methods: We analysed serum 25OHD levels in 234 women with GDM and 168 controls. To define deficiency status, maternal serum levels of 25OHD were further classified into four groups (<12.5 nmol/l as severely deficient, 12.5–24.9 nmol/l as deficient, 25–49.9 nmol/l as insufficient and ≥50 nmol/l as sufficient, respectively).

Results: Women with GDM had significantly lower 25OHD levels compared to controls (30.8±16.3 vs 36.0±16.2 nmol/l, P=0.002). However, when subgroups of 25OHD were analysed, GDM was significantly more common only in women with severely deficient 25OHD level. After adjusting for covariates including maternal age, previous history of GDM, history of type 2 DM in first degree relatives and pre-pregnancy BMI, only severely deficient 25OHD levels were independently associated with an increased relative risk of GDM (OR=3.95, 95% CI, 1.68–9.25, P=0.002). The odds ratios of GDM in women with insufficient and deficient 25OHD levels were not statististically significant (OR=1.46, 95% CI, 1.27–2.74, P=0.23, OR=1.64, 95% CI, 1.26–3.43, P=0.18, respectively). PTH concentrations were also significantly higher in women with GDM compared to controls (45.3±26.2 vs 38.7±27.6 pg/ml, P=0.016).

Conclusions: Results from this study provide novel data indicating that only severely deficient maternal serum 25OHD level is significantly associated with an elevated relative risk of GDM, even after adjusting for established risk factors of GDM. Large-scale, well-designed and multi-center studies are required to further evaluate this relationship.