First-Trimester Circulating 25-Hydroxyvitamin D Levels and Development of Gestational Diabetes Mellitus

OBJECTIVE: To investigate the association between first-trimester maternal serum levels of 25-hydroxyvitamin D (25-OH-D) as measured by liquid chromatography-tandem mass spectrometry and development of gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: We conducted a case-control study involving 248 women in the first-trimester of pregnancy, 90 of whom developed GDM and 158 remained normoglycemic. RESULTS: Although booking 25-OH-D levels correlated negatively with 2-h glucose post-oral glucose tolerance test and positively with HDL cholesterol, as well as with ethnicity, obesity, and smoking (all P < 0.05), there were no statistically significant differences in baseline maternal mean 25-OH-D levels between those who subsequently developed GDM, 18.9 ng/mL (SD 10.7) and those who remained normoglycemic, 19.0 ng/mL (10.7) (P = 0.874), even after adjustment for possible confounders including sampling month (P = 0.784). CONCLUSIONS: Our large and well-phenotyped prospective study did not find evidence of an association between first-trimester maternal levels of 25-OH-D and subsequent development of GDM.