妊娠期糖尿病与维生素D缺乏相关

柏林——欧洲糖尿病研究协会(EASD)年会上公布的一项研究显示，孕早期维生素D缺乏与孕中期发生妊娠期糖尿病的风险显著增加相关。此外，研究结果显示维生素D缺乏与妊娠期糖尿病发生率增加之间的显著关联可归因于胰岛素抵抗增加。

这项研究纳入655例妊娠6~13周的≥18岁单胎妊娠女性。受试者无糖尿病或妊娠期糖尿病、流产、酒精或药物滥用史。研究者在妊娠6~13周时测定各例女性的血液25羟基维生素D水平，并在24~28周时对各例女性进行糖尿病评估。研究期间，54例(8%)女性发生妊娠期糖尿病。

在孕中期血糖正常的601例女性中，26%在孕早期存在维生素D缺乏(血液水平＜50 nmol/L)，在孕中期发生妊娠期糖尿病的女性中，37%在孕早期存在维生素D缺乏。校正年龄、采血时间、维生素D补充剂使用情况和肥胖程度后发现，孕早期血液25羟基维生素D水平每降低1个标准偏差(相当于19 nmol/L)，孕中期发生妊娠期糖尿病的风险显著增加40%。

该分析还在发生妊娠期糖尿病的女性中发现平均松田指数(Diabetes Care 1999;22:1462-70)和胰岛素分泌敏感性指数均显著降低(Diabetic Medicine 2009;26:1198-1203)。这些指标降低提示低维生素D水平与妊娠期糖尿病之间的关联与胰岛素抵抗有关。

专家评论：维生素D与胰岛素抵抗

帝国理工学院医院内分泌科医生Anne Dornhorst博士表示，目前已发现维生素D及其活性代谢产物在胰岛素抵抗和胰岛素抵抗的表达中发挥作用，而胰岛素抵抗又是妊娠期糖尿病发生的基础，因此维生素D已成为研究妊娠期糖尿病的重要线索。目前有研究者正在研究补充维生素D在预防妊娠期糖尿病中的作用。

研究者及Dornhorst博士博士均声明无经济利益冲突。

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By: MITCHEL L. ZOLER, Ob.Gyn. News Digital Network

BERLIN – Vitamin D deficiency during the first trimester of pregnancy linked with a significantly increased risk for the development of gestational diabetes by the second trimester in a study of 655 pregnant women.

The study results also indicated that increased insulin resistance explained the significant association between vitamin D deficiency and an increased incidence of gestational diabetes, Marilyn Lacroix said at the annual meeting of the European Association for the Study of Diabetes.
 
The analysis showed that for every standard-deviation decrease in blood levels of 25-hydroxyvitamin D identified during the first trimester, women had a statistically significant 40% increased rate of having gestational diabetes during their second trimester, after adjustment for age, season of blood sampling, use of vitamin D supplements, and degree of adiposity, reported Ms. Lacroix, an endocrinology researcher at Sherbrooke (Que.) University. In the population studied, a standard-deviation reduction in blood levels of vitamin D corresponded to a drop of 19 nmol/L.

The study included 655 pregnant women aged 18 or older at 6-13 weeks’ gestation with a singleton pregnancy and no history of diabetes or gestational diabetes, miscarriage, or alcohol or drug abuse. The researchers measured each woman’s blood level of 25-hydroxyvitamin D at gestational week 6-13, and then assessed each woman for diabetes at week 24-28. During the study, 54 of the women (8%) developed gestational diabetes.

The prevalence of first-trimester vitamin D deficiency – a blood level of less than 50 nmol/L – was 26% among the 601 women who were normoglycemic during the second trimester, and 37% among women who developed gestational diabetes by the second trimester.

The analysis also showed a significantly reduced average Matsuda index (Diabetes Care 1999;22:1462-70), as well as a significantly reduced insulin secretion sensitivity index (Diabetic Medicine 2009;26:1198-1203) among patients who went on to have gestational diabetes. These reductions suggest that insulin resistance forms the link between low vitamin D levels and incident gestational diabetes, Ms. Lacroix said.

Ms. Lacroix reported that she and her associates also had no relevant financial disclosures.
 
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Vitamin D and Insulin Resistance

Researchers now recognize that vitamin D and its active metabolites play a role in insulin resistance and the expression of insulin resistance. It is also known that insulin resistance underpins the development of gestational diabetes, and as a result vitamin D has become recognized as an important line of research for studying gestational diabetes. If there is any time when vitamin D is important, it is during pregnancy. Insulin resistance increases during pregnancy; pregnant women have up to a threefold drop in insulin sensitivity, and vitamin D probably has a role in this, according to Dr. Anne Dornhorst.

Compounding a woman’s risk during pregnancy is the growing prevalence of vitamin D insufficiency and deficiency, especially in areas such as where I practice in London where many women are at risk because of their dark skin, their body covering, or both.

Dr. Lacroix’s findings are what we would expect. Her report highlights vitamin D’s emergence as a key to understanding insulin resistance. The next step is to assess the role of vitamin D supplementation in reducing gestational diabetes, and studies looking at this are now underway.

DR. DORNHORST is an endocrinologist at the Imperial College Hospital and senior diabetologist at Charing Cross and Hammersmith Hospitals, all in London. She said that she had no relevant financial disclosures. Dr. Dornhorst made these comments in an interview.