The Impact of Vitamin D Supplementation on Glucose Metabolism in Chinese Women With Former Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance that is first identified during pregnancy, excluding diabetic patients diagnosed before pregnancy. GDM can not only have an adverse effect on the pregnant women and the developing fetus, but also can have long lasting effects after birth. GDM can elevates risks of abnormal glucose metabolism postpartum. Vitamin D deficiency has been shown to be associated with insulin resistance and impaired β-cell function. Our previous research also implied that the level of vitamin D is much lower in the women of impaired glucose regulation after birth with history of GDM. This prospective randomized, control clinical trial was designed to evaluate the effects of vitamin D administration on insulin resistance and β-cell function among women with vitamin D deficiency（25OHD \<50 ng/mL）and previous GDM. Participants with vitamin D deficiency and previous GDM were divided into normal glucose regulation group(NGR) (n=90) and impaired glucose regulation group(IGR)(n=90) according to the oral glucose tolerance test (OGTT) around 42 days postpartum. And each group was further divided into intervention group and control group, Participants in the intervention group took 1600 units of vitamin D daily for nine months and meanwhile receive lifestyle intervention. The control group only receive lifestyle intervention. This study aimed to evaluate the impact of vitamin D supplementation on insulin sensitivity, pancreatic β-cell function and markers of inflammation in Chinese women with former GDM and vitamin D insufficiency.