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.
Clifton-Bligh
R J
RJ
Department of Endocrinology, Royal North Shore Hospital, St Leonards, NSW, Australia.
McElduff
P
P
McElduff
A
A
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