Association Of Vitamin D And Parathyroid Hormone With Glucose Metabolism During The Second Trimester

ObjectiveTo exploring the relationship between different statuses of vitamin D and parathyroid hormone?PTH?during the second trimester with glucose metabolism indexs and the risk of gestational diabetes mellitus?GDM?.MethodsA total of 4 799 21 to 24 weeks single pregnant women who had antenatal care in 3hospitals of Hefei from March 2015 to December 2017 were recruited.Questionnaires were conducted and serum 25-hydroxyvitamin D and PTH levels were measured in fasting venous blood.Oral glucose tolerance test was performed during 24 to 28 weeks.Pregnant women with diabetes before conception,severe pregnancy complications,liver and kidney dysfunction,thyroid dysfunction,assisted reproduction,uncomplete information were excluded from the study,4 138 pregnant women were included finally.1 800 pregnant women'fasting blood samples were randomly selected for PTH detection,and 168 samples'results below the lower limit of detection were excluded,the number of PTH subjects was 1 632.Differences in glucose metabolism indexs were analyzed by multivariate linear regression analysis in pregnant women with different vitamin D and PTH groups respectively.Orthogonal design with Vitamin D?non-deficiency and deficiency?and PTH?low to medium levels and high level?were applied,multivariate linear regression models and multivariate logistic regression models were applied to analyze the differences of glucose metabolism indexs and GDM risk among pregnant women at different statues of vitamin D combinated PTH.ResultsThe average level of 25?OH?D in the second trimester was?39.8±16.6?nmol/L,with the median PTH 10.7 ng/L(P₂₅=6.9 ng/L,P₇₅=16.7 ng/L),and the detection rate of GDM 19.6%.The factors relating to 25?OH?D were BMI before pregnancy,enrolled seasons and the intake frequency of post-pregnancy calcium tablets,cod liver oil,and vitamin D supplements,multivitamins,milk,egg yolk,dessert for the past week more than 3 times per week and sun exposure,;The factors relating to PTH were pregnant age,BMI before pregnancy,place of residence,parity,enrollment seasons,milk intake in the recent week more than 3 times and sun exposure,physical activity.Comparing with vitamin D non-deficiency group,glucose metabolism indexs in the vitamin D severely deficient group was no statistically significant difference,and the FPG level in the vitamin D mild deficiency group were significantly higher than control group;the glucose metabolism indicators was no statistical difference in different PTH groups.Orthogonal design with Vitamin D and PTH were grouped,pregnant women with high PTH and vitamin D deficiency?group 3?had higher PG-1h and AUC_glu levels,compared with pregnant women with middle-lower PTH and vitamin D deficiency?control group?(adjusted PG-1h?=0.383,95%CI:0.084⁰.683;adjusted AUC_glu?=0.492,95%CI:0.111⁰.874;adjusted GDM OR=1.61,95%CI:1.04².50),However,significant changes in glucose metabolism indicators and GDM risk were not observed in middle-lower PTH and vitamin D deficiency group?group 1?and high PTH with vitamin D non-deficiency group?group 2?.Further analysis was performed,when PTH at a high level,pregnant women with vitamin D deficiency?Group 3?had higher PG-1h and AUC_glu levels than vitamin D non-deficiency group?group 2?(adjusted PG-1h?=0.470,95%CI:0.052⁰.888;adjusted AUC_glu?=0.638,95%CI:0.107¹.170;adjusted GDM OR=1.89,95%CI:1.001³.843).ConclusionsThere is an interaction between vitamin D level and PTH level with glucose metabolism during pregnancy,the effect of vitamin D deficiency on abnormal glucose metabolism may depend on PTH level.When paying attention to the relationship between vitamin D and glucose metabolism during pregnancy,the statuses of PTH cannot be ignored,otherwise,more research should be conducted to explore the role of the vitamin D-PTH axis in the homeostasis of glucose metabolism.