Role of HbA1c and 50g GCT in early detection and prediction of gestational diabetes and associated maternal and fetal complications in Thailand

妊娠期高血糖被称为妊娠期糖尿病（GDM），是妊娠期最常见的疾病之一。它会对孕妇和她的孩子造成伤害。GDM影响了10-15%的泰国女性。现在越来越多的女性被诊断为GDM，因为较低的血糖水平被用来诊断GDM。如果不治疗，GDM会导致妊娠期高血压、剖腹产数量增加、焦虑和抑郁。患有GDM的女性一生中患2型糖尿病（T2DM）的风险高出7-8倍。孩子们也有危险。它们可能太大或太小。如果太大，他们的肩膀可能会在分娩时受损。他们的血糖可能在出生后降得太低。他们可能在出生后不久就出现黄疸，或者呼吸困难。极少数可能在出生前死亡（死胎）。从长远来看，这些孩子患超重和糖尿病的风险更高。GDM的诊断通常在妊娠24-28周之间进行，使用葡萄糖饮料试验称为口服葡萄糖耐量试验（OGTT）。虽然治疗可以改善妊娠结果，但有些损害可能已经对未出生的婴儿造成了。因此，在怀孕早期检测高血糖水平可能会更好。然而，筛查有好处也有坏处。正如《英国医学杂志》最近的一篇文章所说：“妊娠糖尿病的标签带来了一系列干预措施，包括血糖监测、额外的诊所就诊、更多的产科监测（更有可能引产）、手术分娩和婴儿入院接受特殊护理，最后对母亲来说是糖尿病高风险的标签。”有些人认为所有女性都应该接受OGTT筛查，但这可能是不必要的。该测试要求孕妇至少在8小时内没有吃任何东西。在包括英国在内的许多国家，选择女性进行OGTT是基于超重和年龄较大等风险因素。然而，根据这些因素选择女性可能会错过多达一半的GDM女性。在泰国，GDM高危妇女应该在第一次产前门诊就诊时进行50g葡萄糖激发试验（GCT）筛查。但是，泰国的GDM筛查率从农村地区的零到城市的78%不等。另一种简单的手指穿刺血糖测试（称为HbA1c）可能可以代替。这将在第一次产前诊所就诊时进行。糖化血红蛋白是一步检测，患者不需要禁食。然而，HbA1c检测在泰国女性中的价值尚不清楚。本研究的目的是发现首次产前就诊时的HbA1c和50g GCT检测是否可以预测晚期GDM，以及是否存在一个可以排除晚期GDM的水平。我们还想比较所有孕妇的检测和只检测那些有危险因素的孕妇。我们将进行一项试验，看看饮食和生活方式干预是否能预防女性患上GDM。准确的HbA1c和50g GCT水平可以安全地排除低风险女性的GDM，这将有助于孕妇。他们可以放心了。避免对OGTT的需要将节省他们的时间和金钱。相反，如果HbA1c和50g GCT水平将他们确定为高危人群，健康的饮食和生活方式建议可以降低他们患GDM的风险。除了对母亲及其子女有益之外，这项研究也将对在泰国提供保健服务的人员有用。他们可以更多地关注高危女性。研究结果可供其他国家使用。

High blood glucose levels in pregnancy called gestational diabetes mellitus (GDM) is one of the most common medical conditions during pregnancy. It can cause harm to the pregnant woman and her child. GDM affects 10-15% of Thai women. More women are being diagnosed with GDM now because a lower level of blood glucose is being used to diagnose GDM.If not treated, GDM can cause high blood pressure in pregnancy, increased numbers of caesarean deliveries, anxiety and depression. Women who have had GDM have 7-8 times higher life-time risk of type 2 diabetes mellitus (T2DM). There are risks to the children too. They may be too big or too small. If too big, they can have shoulders damaged during the birth. Their blood glucose may fall too low after birth. They may get jaundice soon after birth, or have difficulty in breathing. A very few may die before birth (stillbirth). In the long term, these children are at higher risk of becoming overweight and diabetic.The diagnosis of GDM is usually made between 24-28 weeks of pregnancy using a glucose drink test called an oral glucose tolerance test (OGTT). Although treatment can improve pregnancy outcomes, some of the damage may have already been done to the unborn baby. So screening to detect high glucose levels earlier in pregnancy may be better. However, there can be harms as well as benefits from screening. As a recent British Medical Journal article said:"a label of gestational diabetes brings with it an intervention package that includes glucose monitoring, extra clinic visits, more obstetric monitoring with greater likelihood of labour induction, operative delivery and admission of the baby to special care, and finally for the mother a label of high risk for diabetes". Some people think that all women should be screened with OGTT has been advocated but that may not be needed. The test requires pregnant women to come to a clinic having not eaten anything for at least 8 hours. In many countries including the UK, women are selected for OGTT based on risk factors such as overweight and older age. However, selecting women based on these factors can miss up to half of all women with GDM. In Thailand, women at high risk for GDM are supposed to be screened at the first antenatal clinic visit with the 50g Glucose Challenge Test (GCT). But, the rate of screening for GDM in Thailand varies from none at all in rural areas to 78% in cities. Another blood glucose test done by a simple finger prick (called HbA1c) might do instead. It would be done at the first antenatal clinic visit. The HbA1c is a one-step test and patients do not need to fast. However, the value of HbA1c testing is not yet known in Thai women.The aims of this study are to find out whether HbA1c and 50g GCT testing at first antenatal clinic visit can predict later GDM and if there is a level that can rule out later GDM. We also want to compare testing of all pregnant women with testing only those with risk factors. We will do a trial to see if diet and lifestyle interventions can prevent women developing GDM.Accurate HbA1c and 50g GCT levels that can safely rule out GDM in women at low risk would help pregnant women. They can be reassured. Avoiding the need for OGTT would save them time and money. In contrast, if the HbA1c and 50g GCT levels identifies them as at high-risk, healthy eating and lifestyle advice can reduce their risk of getting GDM. In addition to the benefit to mothers and their children, this study will also be useful to people who provide health care in Thailand. They can focus care more on women at high risk. The results could be used by other countries.