Gestational diabetes is a condition related to glucose metabolism that develops only during pregnancy, where the body becomes intolerant to glucose.
In Singapore, one in about every five pregnancies leads to gestational diabetes1. To understand this condition, it is important to first understand how our body processes sugar in normal conditions.
Sugar, our main fuel for our body cells, requires insulin to be able to enter the body cells from the bloodstream. During pregnancy, hormones make the pregnant woman naturally more resistant to the action of insulin, so that the sugar she eats can be shared between her and her baby.
In normal situations, more insulin is produced in order to keep blood sugar levels normal. In some cases, this does not happen and blood sugar levels increase, leading to what is called gestational diabetes (GDM).
WHO IS AT RISK OF DEVELOPING GDM2,3?
- are more than 30 years of age have a body mass index (BMI) of more than 25 for non-Asians and 23 for Asians
- have a past history of GDM
- have first-degree relatives with type 2 diabetes mellitus
- are of South-East Asian, Pacific Island, Hispanic, African, or Native American descent
WHAT PROBLEMS CAN GDM CAUSE?
GDM can lead to the following4:
- an increased risk for preeclampsia and emergency caesarean delivery (c-section)
- a large baby, which can result in complications during the delivery (macrosomia)
- the baby developing low blood sugar levels after birth (neonatal hypoglycaemia)
- stillbirth (very rare)
- a predisposition to childhood obesity for the infant
The mother also has a higher risk of developing type 2 diabetes mellitus. Studies show that 13% of moms develop type 2 diabetes after just 5 years postpartum, and almost 19% develop it 9 years postpartum5.
It is important to highlight that if the pregnant woman has a high BMI and GDM, then she will have a greater risk of complications as compared to if she only had one of them.
HOW DO I TEST IF I HAVE GDM?
A screening is usually done between 24 to 28 weeks of pregnancy. If you are at higher risk of having GDM, your doctor may recommend you perform the test earlier. In Singapore, it is recommended that all pregnant women undergo the screening test irrespective of risk factors6.
There are several ways to screen for GDM. The most common test is the Oral Glucose Tolerance Test (OGTT). The OGTT has been recommended by the American Diabetes Association, the Australasian Diabetes in Pregnancy Society, the World Health Organization (WHO), the College of Obstetricians and Gynaecologists, Singapore, and other global official bodies6.
For this test, you will first do a blood test to check your blood sugar levels in the morning after fasting. Then you will be given 75g of glucose (sugar) to drink. Another two blood samples will be taken, one after an hour and the other two hours later. You will be diagnosed with GDM if you have one or more elevated blood sugar values (above normal limits) on any of the blood tests.
HOW IS GDM TREATED?
Just like diabetes, GDM cannot be cured; it can only be controlled. However, in most cases, it resolves soon after giving birth.
The first-line treatment of GDM is Medical Nutrition Therapy (MNT) provided with the advice of a dietitian2. Even though most pregnant women can control their blood sugar levels through diet and exercise alone, about 15-30% may require drug therapy most frequently, insulin therapy,5,6.
The goals of MNT are to help the pregnant woman achieve a healthy diet, while promoting an appropriate maternal weight gain and foetal growth4.
IS IT NECESSARY TO SEE A DIETITIAN?
Research has shown that comprehensive nutritional intervention and individualization of MNT is effective in improving blood sugar levels control, and neonatal and maternal outcomes in women with GDM. Improved outcomes included4:
- lower birth weight
- reduction in the need for insulin therapy reduction of hypertensive disorders of pregnancy, and maternal hospitalizations reduction of neonatal intensive care unit admissions and neonatal deaths
- reduction of premature births
- reduction of rates of shoulder dystocia (where the baby’s shoulder becomes wedged behind the mother’s pubis – sometimes this happens because the baby is too big to fit through the birth canal)
- reduction of bone fracture during the delivery reduction of nerve palsies
If you are at high risk for GDM, it is important to seek the advice of a dietitian early in your pregnancy. Several studies supporting this have reported a reduction of GDM incidence in women with higher BMI or a history of GDM, if they consulted a dietitian early4.
WHAT HAPPENS IN A CONSULTATION WITH THE DIETITIAN?
The first consultation usually lasts about 50 minutes, during which a comprehensive diet, medical, family, and social history are taken. The dietitian may also ask you about your appetite, use of supplements, physical activity, and functional levels.
The dietitian will also assess your height, weight, pre-pregnancy weight, BMI, and weight changes during pregnancy. Through the assessment of these factors, the dietitian makes a nutritional diagnosis and formulates a nutritional plan.
No one rule fits all when it comes to the management of GDM. The intervention is dependent on the specific details of each individual case. It may include an explanation of the link between your condition and your diet, and education on the general guidelines for gestational diabetes, or a detailed meal plan with a recommendation of your dietary carbohydrates. Sometimes you might not require a meal plan on your first consultation. The dietitian may work with you on ways to modify your current diet in order to help you control your blood sugar levels better and address other issues that might have been picked up in the nutritional diagnosis.
Throughout your consultations, you may learn (depending on your assessment and outcomes) about:
- overall healthy eating
- how to count carbohydrates
- how to distribute your carbohydrates throughout your day
- glycaemic index
- types of fats and what is healthy dietary fibre
- how to read food labels
- strategies on how to eat out
- how to have a healthy diet after the pregnancy
Do note that this is not a comprehensive list, and it may change according to your specific needs. If it is not contraindicated, your dietitian will also encourage you to exercise.
You will need to closely check your blood sugar levels both before and after your meals. Your doctor or dietitian will discuss the ideal frequency of self-monitoring with you. Most women typically should check their blood sugar levels at least four times a day- once before eating in the morning, and one or two hours after breakfast, lunch, and dinner respectively. The more closely you monitor your blood sugar levels, the better the outcomes.
HOW MANY DIETITIAN APPOINTMENTS WILL I REQUIRE?
Visits to a dietitian should be regular and frequent in order to optimise outcomes. It is recommended to have at least 3 visits in the first 4-5 weeks. Additional visits should be scheduled after every 2-3 weeks or as needed for the duration of the pregnancy. The regular visits will help you meet your blood glucose level and weight gain targets, have a well-balanced diet, and promote your and your baby’s well-being4.
WHAT ARE MY BLOOD SUGAR LEVEL GOALS?
Depending on your country’s unique guidelines, the values for target levels may change – so always check with your doctor. Some organizations (American Diabetes Association and the American College of Obstetricians and Gynaecologists) recommend the following8:
- Fasting: <5.3mmol/L (95 mg/dL)
- One hour after meal: <7.8 mmol/L (140 mg/dL)
- Two hours after meal:< 6.7 mmol/L (120 mg/dL)
In Singapore, these are the blood sugar levels targets6:
- Fasting: 4.4-5.5 mmol/I AND
- One hour after meal:< 7.8 mmol/I OR
- Two hours after meal: 5.5-6.6 mmol/I
WHEN DO I REQUIRE INSULIN OR OTHER PHARMACOLOGICAL TREATMENT?
When to initiate treatment is dependent on the clinical judgement of your doctor, as there are currently no clear guidelines on this.
Some recommendations suggest insulin for two or more elevated values in a two-week interval, while others await more consistent elevations, particularly if it is judged that further nutritional counselling may be effective.
CAN I JUST AVOID CARBOHYDRATES ALTOGETHER WHEN DIAGNOSED WITH GDM?
No! You and your baby require a minimal amount of carbohydrates every day in order to support pregnancy. Besides, foods rich in carbohydrates will also contain other nutrients that are crucial to the pregnancy such as B vitamins (e.g. folate), magnesium, iron, fibre, and phyto-nutrients.
Guidelines recommend all pregnant women, including those with GDM, have a minimum of 175g of carbohydrates each day4. This is a substantial amount, especially when compared to low carbohydrate diets. The trick is to know which type of carbohydrates to eat, when to eat, how much to eat each time, and when to include exercise.
I WAS DIAGNOSED WITH GDM BUT WHEN TESTING MY BLOOD SUGAR LEVELS AT HOME, I WAS WITHIN THE NORMAL RANGE; WAS I DIAGNOSED WRONGLY?
When you do the OGTT test, you test the capability of your body to process a certain amount of sugar at one go (usually 75g). If you tested your blood sugar levels after a meal and they are normal, it’s great news – it means you are probably eating an amount of carbs that your body can still process.
However, you should continue to monitor your blood sugar levels as sometimes, it gets more difficult to control the blood sugar levels as the pregnancy progresses.
HOW MUCH EXERCISE IS ADVISED IF NOT CONTRAINDICATED?
It is recommended to perform daily moderate exercise of 30 minutes or more per day. Aerobic and non-weight-bearing exercises such as stretching, swimming, and yoga have been shown to lower blood glucose levels in women with GDM when combined with a healthy diet4,6,8. Personally, I always recommend the pregnant woman go for at least a 10-15 minute walk after each meal. Pregnant women find it easier to control their blood sugar levels if they follow this guideline.
CAN I STILL HAVE SWEETS AND DESSERTS IF I AM DIAGNOSED WITH GDM?
Even though it is not recommended to have sweets and desserts frequently, women with GDM can still occasionally indulge in their favourite sweets. However, it is important that you plan when and how much you are going to have; talk to your dietitian about it.
I recall a consultation with a pregnant woman who started crying unexpectedly during her second visit, expressing that all she wanted was a small piece of chocolate. We had never discussed it until then since it was not brought up when talking about her diet history. Since then, I make it a point with all my clients to calculate how much and when they can have some chocolate (I usually recommend dark chocolate) or other sweets if they crave them.
HOW CAN I REDUCE MY RISK OF HAVING TYPE 2 DIABETES AFTER BEING DIAGNOSED WITH GDM?
Breastfeeding may decrease the long-term risk of developing type 2 diabetes9,10.
Maintaining a healthy diet and active lifestyle also helps reduce the risk of developing type 2 diabetes11. In a study, women who maintained a total moderate-intensity activity level of at least 150 minutes per week, or 75 minutes per week of vigorous-intensity exercise, had a 30 to 50 percent lower risk of developing type 2 diabetes, compared to women who did not achieve this level of activity12.
AFTER DELIVERY, DO I NEED TO BE TESTED FOR TYPE 2 DIABETES?
The American College of Obstetricians and Gynaecologists recommends all women with GDM be tested 6 to 12 weeks after delivery to exclude type 2 diabetes. This testing should be done at regular intervals of at least 2 to 3 years. In women with more risk factors, such as obesity, a family history of type 2 diabetes, and insulin requirements during pregnancy, this testing should be done every year6.
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This article was first published on Jan 2019 on Stork’s Nest Global Facebook page.
- Health Promotion Board. Gestational Diabetes What You Need To Know. [Online] Sep 25, 2018. [Cited: Jan 21, 2019.] https://www.healthhub.sg/live-healthy/1606/gestational-diabetes-what-you-need-to-know.
- Hartling, L., Dryden, D.M., Guthrie, A. et al. Screening and diagnosing gestational diabetes mellitus. Evid Rep Technol Assess (Full Rep). 2012; : 1–327
- Moyer, V.A. and US Preventive Services Task Force. Screening for gestational diabetes mellitus: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2014; 160: 414–420
- Duarte-Gardea, Maria O. et al. Academy of Nutrition and Dietetics Gestational Diabetes Evidence-Based Nutrition Practice Guideline. Journal of the Academy of Nutrition and Dietetics , Volume 118 , Issue 9 , 1719 – 1742. Available at https://jandonline.org/article/S2212-2672(18)30365-4/fulltext
- Catalano, P.M., McIntyre, H.D., Cruickshank, J.K. et al. The hyperglycemia and adverse pregnancy outcome study: Associations of GDM and obesity with pregnancy outcomes. Diabetes Care. 2012; 35: 780–786
- College of Obstetricians and Gynaecologist, Singapore. Guidelines for the management of Gestational Diabetes Mellitus (12 Jan 2018). Available at https://ams.edu.sg/view-pdf.aspx?file=media%5C4163_fi_430.pdf&ofile=COGS+GDM+Guidelines+2018.pdf
- Society of Maternal-Fetal Medicine (SMFM) Publications Committee.. SMFM Statement: Pharmacological treatment of gestational diabetes. Am J Obstet Gynecol 2018; 218:B2.
- Durnwald, C. UpToDate Patient education: Gestational diabetes (beyond the basis). Dec 2018 https://www.uptodate.com/contents/gestational-diabetes-beyond-the-basics?search=gestational%20diabetes%20patient%20education&source=search_result&selectedTitle=3~57&usage_type=default&display_rank=3#H1
- Gunderson EP. Breastfeeding after gestational diabetes pregnancy: subsequent obesity and type 2 diabetes in women and their offspring. Diabetes Care 2007;30(Suppl 2):S161–8. 25.
- Kim C, Chames MC, Johnson TRB. Identifying post-partum diabetes after gestational diabetes mellitus: the right test. Lancet Diabetes Endocrinol. 2013; 1: 84–6.
- Balk EM, Earley A, Raman G, et al. Combined Diet and Physical Activity Promotion Programs to Prevent Type 2 Diabetes Among Persons at Increased Risk: A Systematic Review for the Community Preventive Services Task Force. Ann Intern Med 2015; 163:437.
- Physical Activity Guidelines Committee. Physical Activity Guidelines Advisory Committee Report. Washington, DC: Department of Health and Human Services; 2008: http://www.health.gov/paguidelines/report.