Maternal vitamin D deficiency, ethnicity and gestational diabetes.
OBJECTIVE
Vitamin D deficiency has been linked to impaired glucose metabolism. We determined whether serum 25-hydroxyvitamin D (25OHD) is associated with glucose metabolism in pregnant women and the effect of ethnicity on this relationship.


METHODS
We analysed serum 25OHD concentrations in 307 pregnant women attending a metropolitan obstetric clinic between October 2003 and May 2005. Measurements from 264 of the women were taken at the time of glucose tolerance testing at mid-gestation, a population therefore at increased risk for gestational diabetes. Pearson correlation analysis was used to test for univariate linear relationships between the natural log of serum 25OHD (ln-25OHD) and other variables. Multiple regression analysis was used to adjust for confounding factors.


RESULTS
Mean serum 25OHD concentration was 53.8 +/- 23.9 nmol/l (sd). Ln-25OHD was negatively correlated with serum parathyroid hormone as expected (r -0.24, confidence intervals -0.35 to -0.12). Ln-25OHD was also negatively correlated with fasting plasma glucose (r-0.20, -0.31 to -0.08), fasting insulin (r -0.20, -0.31 to -0.08) and insulin resistance as calculated by homeostasis model assessment (r -0.21, -0.32 to -0.09). The association between fasting glucose and log-transformed 25OHD concentration was of borderline significance after accounting for ethnicity, age and body mass index in multivariate analyses (-0.13, -0.26 to 0.01). The odds ratio of gestational diabetes in women with 25OHD < 50 nmol/l did not reach statistical significance (1.92, 95% confidence interval 0.89-4.17).


CONCLUSIONS
Maternal 25OHD concentrations are inversely related to fasting glucose, although further studies are required to establish whether this is independent of the effects of ethnic background.
Department of Endocrinology, Royal North Shore Hospital, St Leonards, NSW, Australia.
R J
RJ
Clifton-Bligh
P
P
McElduff
A
A
McElduff
D000328:Adult; D016640:Diabetes, Gestational / Q000208:ethnology / Q000378:metabolism*; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000378:metabolism; D006801:Humans; D010281:Parathyroid Hormone / Q000378:metabolism*; D011247:Pregnancy; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000208:ethnology / Q000378:metabolism*
D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D