Endocrine Abstracts

Introduction: The relation between vitamin D deficiency and gestational diabetes mellitus (GDM) has been rarely addressed in the literature with conflicting results. The aim is to determine the association between maternal serum 25(OH)D and glucose metabolism in Caucasian pregnant women.

Patients and methods: In a prospective study 157 pregnant women aged 31.2±5.8 years underwent a 100 g OGTT in the third trimester of pregnancy, during which serum 25(OH)D, PTH, Ca, and P concentrations were also measured. For GDM diagnosis the ADA 2000 criteria were used. For 25(OH)D deficiency a cut-off point of 20 ng/ml was chosen. Age, height, pre-pregnancy weight, BMI and blood pressure (BP) were recorded. Indices of insulin secretion and sensitivity were calculated. 25(OH)D was converted to its natural logarithm (Ln).

Results: 25(OH)D deficiency was found in 88 out of 157 pregnant women (56%). There was no difference in mean serum 25(OH)D between normal (n=95, 20.2±7.0 ng/ml), isolated hyperglycaemia (n=30, 22.1±7.7) and GDM (n=32, 19.4±8.3) women. Ln-25(OH)D was negatively correlated with fasting plasma glucose (r=−0.174, 95% CI 0.020–0.326, P=0.029). The relationship remained significant after adjustment for BMI, age, gestational age and seasonal variation. The percentage of isolated fasting hyperglycaemia (Glu0′≥95 mg/dl) was significantly increased in the subgroup of pregnant women with vitamin D deficiency (<20 ng/ml) compared to their counterparts with 25(OH)D>20 ng/ml (27.3 vs 7.2% respectively, P<0.01). The odds ratio of isolated fasting hyperglycaemia in women with 25(OH)D<20 ng/ml was 4.8 (95% CI 1.7–13.3). No correlation was found between Ln-25(OH)D and indices of insulin secretion or resistance. We confirmed the expected negative correlation of Ln-25(OH)D with PTH (r=−0.446, P<0.001) and also with systolic (r=−0.203, P=0.011) and diastolic BP (r=−0.238, P=0.003).

Conclusion: We found an independent negative correlation of 25(OH)D with fasting glucose in pregnant women. Furthermore 25(OH)D deficiency was significantly associated with increased risk for isolated fasting hyperglycaemia. Finally 25(OH)D deficiency is common in Greek pregnant women.