Gestational diabetes is hyperglycaemia (high blood sugar) that develops during pregnancy and can disappear after giving birth (NHS, 2019). The current rate of developing gestational diabetes for pregnant women in the UK is approximately 16%, where risk factors like having a BMI (body mass index) above 30, having gestational diabetes in a previous pregnancy, or if you are of South Asian, Black, African-Caribbean or Middle Eastern origin, increase your likelihood (Diabetes, 2021).
Due to lots of changes occurring in the body during pregnancy, the hormones that you produce can prevent insulin from being used properly. Normally, the insulin your body produces allows glucose (sugar) to be used for energy, but pregnancy can put you at an increased risk of insulin resistance. Consequently, the glucose stays in the blood and the sugar levels rise, causing gestational diabetes (Diabetes, 2021). Often, women present as asymptomatic, unless they are hyperglycaemic at all times, as some pregnancy symptoms can be crossed with normal non-pregnant diabetic symptoms.
Typically, it is diagnosed between the 24th and 28th week of pregnancy by using a glucose tolerance test that measures how quickly the glucose, from a glucose solution drank by the woman, is cleared from the blood. Since hyperglycaemia is continuous, there is not one cut off point to be diabetic and diagnostic testing can become controversial because of this. In practice, there are two screening tests for diagnosing gestational diabetes: one-step, and then two-step (British Medical Journal, 2020).
For one-step testing, a 75g glucose tolerance test is used, although requiring fasting and being a longer test, it is only one step and a blood sugar level cut off was established from a large observational study (Fuller & Borgida, 2014, 148-150).
On the other hand, for two-step testing, a 50g glucose tolerance test is used and requires no fasting, so can be done at any time of the day, but has different accepted values of an abnormal blood sugar level. In contrast, studies found only a small number to have clinically relevant hyperglycaemia (these are the most clinically impacted individuals, which saves some people the adverse impact of a diagnosis of gestational diabetes).
As both tests are usually done in the 24th to 28th week of gestation, scientists have refined nine parameters that can accurately identify which women are at a high risk of developing gestational diabetes, some of which are: the woman’s age; body mass index; family history of diabetes, and results of her glucose tests during previous pregnancies. Having this information available earlier on in the pregnancy can reduce her risk of diabetes through controlling lifestyle measures like exercise and diet (Weizmann Institute of Science, 2020). Undiagnosed diabetes in the first trimester has impacts on the pregnancy, as a baby’s organs, such as the heart, brain, kidneys, and lungs, start forming in the first 8 weeks. High blood glucose levels from gestational diabetes can be harmful and increase the chances of heart defects or brain and spine defects (National Institute of Diabetes and Digestive and Kidney Diseases, 2017). Therefore, asking these nine questions as early on in the pregnancy as possible is vital and can indicate whether blood sugar monitoring should be happening during the pregnancy.
Another recent study, executed in St John’s college in Cambridge, has shown to predict which women will have serious pregnancy complications, like gestational diabetes, through testing hormonal levels in the placenta. Dr Amanda Sferruzzi-Perri says, “We found that hormonal biomarkers from the placenta could indicate which women would have pregnancy complications...these hormonal biomarkers are present from the first trimester of pregnancy.” In this study, researchers looked at proteins made by the placenta and compared them to blood samples from women with ‘uneventful’ pregnancies and those with gestational diabetes. Endocrine cells from the placenta, those responsible for producing hormones (i.e. proteins), were isolated and studied to create a map of proteins. Interestingly, a third of the proteins identified changed in women with pregnancy disorders as early as the 12th week of gestation. In summary, blood samples that show these genetic biomarkers in early pregnancy could lead to the woman’s earlier diagnosis, providing opportunities to prevent the disease or to protect the mum and baby from the harmful complications previously stated (Cambridge University, 2021).
Unfortunately, having gestational diabetes not only increases the risk of developing it in later pregnancies, but also increases the risk of the woman developing type 2 diabetes after giving birth. For example, 30-80% of women with gestational diabetes in their pregnancy develop type 2 diabetes between 5 to 10 years later - all depending on the woman. To counteract this, some oral medications like metformin have been shown to decrease the rate of development of type 2 diabetes (British Medical Journal, 2020).
Thanks to modern medicine, gestational diabetes is monitored and treated successfully, allowing women to carry their babies to full-term pregnancies with a lowered risk of complications. However, more large and randomised clinical trials are needed to improve the accuracy of screening for diagnosis and show effective treatment options for women post-delivery to reduce the risk of developing type 2 diabetes.
Bibliography
British Medical Journal. (2020, November). Gestational Diabetes. BMJ best practice podcast.
Cambridge University. (2021, June 8). Scientists can predict which women will have serious pregnancy complications. Cambridge Research. https://www.cam.ac.uk/research/news/scientists-can-predict-which-women-will-have-serious-pregnancy-complications
Diabetes. (2021, August 31). What is gestational diabetes? Diabetes. https://www.diabetes.org.uk/diabetes-the-basics/gestational-diabetes?gclid=Cj0KCQjwpreJBhDvARIsAF1_BU24EZL0ZSuGPAry4EWnHSThdQ4skn-gnuUYLjKU6PnO2Vj3IiC1XtQaApMeEALw_wcB
Fuller, K. P., & Borgida, A. F. (2014, October). Gestational Diabetes Mellitus Screening Using the One-Step Versus Two-Step Method in a High-Risk Practice. Clinical diabetes: a publication of the American Diabetes Association, 32(4), 148-150. https://doi.org/10.2337/diaclin.32.4.148
National Institute of Diabetes and Digestive and Kidney Diseases. (2017, January). Pregnancy if you have diabetes. NIH. https://www.niddk.nih.gov/health-information/diabetes/diabetes-pregnancy
NHS. (2019). Gestational Diabetes. NHS. Retrieved August 31, 2021, from https://www.nhs.uk/conditions/gestational-diabetes/
Weizmann Institute of Science. (2020, January 15). New algorithm predicts gestational diabetes. Science Daily. www.sciencedaily.com/releases/2020/01/200115120630.htm
