Gestational Diabetes: Understanding the Risks and Managing Your Health During Pregnancy

Gestational diabetes can create a general sense of unease for many pregnant moms due to the lack of understanding around the test, and misinformation from the internet. The oral glucose tolerance test (OGTT) often brings tales of an overly sweet, unpleasant orange drink and nausea horror stories.

Pregnancy is a time of great metabolic shift concerning insulin response and if you have a placenta, as every pregnant woman does, information about gestational diabetes, an explanation of the testing process, understanding the risks, and informed consent options for management help to ensure the well-being of both mother and baby.

What Is Gestational Diabetes?

Gestational diabetes mellitus (GDM) is a state of hyperglycemia, or in layman's terms, elevated blood sugar during pregnancy (Modzelewski et al., 2022). While gestational diabetes is currently the most common antenatal complication, affecting up to 15% of pregnancies worldwide, most pregnant women are without signs or symptoms (Modzelewski et al., 2022). During a normal pregnancy, the mother's body undergoes a series of metabolic adaptations to meet the demands of the growing fetus, including insulin sensitivity (Plows et al., 2018). When normal metabolic adaptations of carbohydrates in pregnancy are inadequate, blood glucose levels can become excessively high, resulting in a GDM diagnosis (Plows et al., 2018). Untreated gestational diabetes causes increased maternal and perinatal morbidity. Treatment reduces these negative pregnancy outcomes.

Options for Gestational Diabetes Testing

In pregnancy, most countries agree that an HgA1c test, early in the first trimester, with values below ≤6.5% blood sugar level is ideal for those with pre-existing risk factors for gestational diabetes (King et al., 2019). These risk factors include having a parent, brother, or sister with type 2 diabetes; being 35 years of age or older; using corticosteroid medication; being obese; having prediabetes; and having gestational diabetes during a prior pregnancy (Feig et al., 2018). However, because this blood test measures an average plasma glucose level over 90 days, the development of gestational diabetes may be missed, and it is not advised for use to diagnose GDM in the second trimester of pregnancy (King et al., 2019).

Current Recommendations for Testing

The “gold standard” of screening for gestational diabetes occurs between the 24th and 28th week of pregnancy. Your doctor or midwife will recommend an oral glucose tolerance test (OGTT). During this screen, expectant mothers consume a 50-gram glucola solution and wait one hour before blood is drawn to measure how well their bodies handle the sugar spike. A normal blood glucose level is below 7.8 mmol/L (Feig et al., 2018). A plasma glucose value above 11.1 mmol/L after this test would indicate gestational diabetes (Feig et al., 2018).

In Canada, if blood sugar levels fall between 7.8-11.0 mmol/L, a second one-part diagnostic test is offered. Expectant mothers undergo a 75-gram, 2-hour OGTT, which requires fasting before the test. This oral glucose tolerance test measures blood sugar after fasting and again at one and two hours after the test. A diagnosis of GDM is made after the second test if the non-fasting plasma glucose value is ≥10.6 mmol/L at 1 hour or ≥9.0 mmol/L at 2 hours (Feig et al., 2018).

Other Screening Alternatives

Many mothers-to-be are interested in food-based or candy-based alternative screening tests due to worry about chemicals, additives, or adverse reactions such as vomiting. However, the effects of different types of sugars and carbohydrates on blood glucose levels vary (Wong & Jenkins, 2007). Glucola uses dextrose specifically; therefore, any other sugar variant like fructose in fruit juices or sucrose in candy, like jellybeans, could lead to a missed diagnosis (Wong & Jenkins, 2007). Most, if not all, laboratories in Canada will not accept this alternative.

Blood glucose monitoring using test strips and a glucose meter during pregnancy.

Another alternative that moms-to-be may discuss with their healthcare providers, instead of doing the OGTT, is to monitor blood sugar levels. This ideally would occur between 26- and 28 weeks gestation, with glucose meter spot testing before and after meals for a few weeks (Negrato & Zadenverg, 2012). Plasma glucose should stay less than 5.3 mmol/L before meals and less than 7.8 mmol/L 2 hours after eating (Feig et al., 2018). However, there is a greater risk for inaccuracy of readings with 30% of meter readings overestimating blood glucose and 55% underestimating readings (Negrato & Zadenverg, 2012).

The last option is to decline all forms of testing after an informed discussion with your doctor or midwife about the pros and cons of opting out.

Understanding the Risks Associated with Gestational Diabetes

Left untreated, gestational diabetes can lead to several serious complications. GDM affects both mother and baby during pregnancy and after. During pregnancy, women with poorly managed gestational diabetes are at increased risk of pre-eclampsia, hypertension, premature delivery, labour induction, and caesarean delivery (Nankervis et al., 2018). Long-term, women with gestational diabetes have a 25.8% cumulative risk 15 years post-pregnancy of developing type 2 diabetes mellitus (Nankervis et al., 2018). The potential complications in neonates are extensive and include macrosomia, stillbirth, shoulder dystocia, nerve palsy, low blood sugar, and respiratory distress (Nankervis et al., 2018). Long-term effects include a predisposition for obesity, blood sugar instability, abnormal blood lipids, and high blood pressure. These metabolic changes can occur as early as three years of age but are firmly established by adolescence in more than 50% of those whose mothers had gestational diabetes (Nankervis et al., 2018).

Managing Gestational Diabetes

It is recommended after a diagnosis of gestational diabetes that expectant mothers self-monitor with a blood glucose meter to check blood sugar several times a day (Feig et al., 2018). Several glucose monitoring options are available from continuous glucose monitors, flash glucose devices, or the more traditional test strips and glucose meters. Proper management is essential for maintaining health during pregnancy and reducing risks to the baby.

Dietary Changes

Effective management begins with dietary changes. Many women work with a dietitian to create a personalized meal plan. This plan usually highlights foods high in fiber, such as whole grains and legumes, while reducing sugar and refined carbohydrates. For instance, integrating foods like lentils, leafy greens, and lean meats can help stabilize blood sugar levels.

Physical Activity

Engaging in regular physical activity can boost insulin sensitivity and aid in controlling blood sugar levels. Activities like walking for at least 30 minutes daily or practicing prenatal yoga are often encouraged, as they can be safe and beneficial.

Medical Intervention

For some women, dietary changes and exercise might not suffice. If blood sugar levels stay high, your doctor or midwife may suggest insulin injections or oral medications, such as metformin, to help control blood sugar. Approximately 15% of women with GDM will require medication to maintain healthy glucose levels throughout their pregnancy (Feig et al., 2018).

Long-term Checkups

Most women with gestational diabetes in pregnancy will return to normal glucose values after delivery, but some will not and will be diagnosed with Type 2 Diabetes going forward. A follow-up glucose tolerance test is recommended 6 weeks to 6 months after the baby is born. If blood sugar levels are normal, experts recommend testing for type 2 diabetes at least every 3 years (Feig et al., 2018). However, if HgA1c test values are 6.0–6.4%, prediabetes is suspected, and diabetic testing is recommended yearly (Feig et al., 2018).

Taking Charge of Your Health During Pregnancy

Knowing about gestational diabetes can transform anxiety into confidence for expectant mothers diagnosed with this condition. Understanding the glucose test and proactive management strategies fosters healthier pregnancy outcomes.

Parent Resources:

Evidence Based Birth Podcast on Screening and Diagnosing Gestational Diabetes

Nurse Tina Discusses Gestational Diabetes

References:

Feig, D. S., Berger, H., Donovan, L., Godbout, A., Kader, T., Keely, E., & Sanghera, R. (2018) 2018 Clinical practice guidelines diabetes and pregnancy. Canadian Journal of Diabetes, 42(2018), S255–S282. Retrieved from https://www.diabetes.ca/DiabetesCanadaWebsite/media/Health-care-providers/2018%20Clinical%20Practice%20Guidelines/Ch36-Diabetes-and-Pregnancy.pdf

King, T. L., Brucker, M. C., Jevitt, C., & Osborne K. (2019) Varney’s midwifery (6th edition). Jones & Bartlett Learning

Modzelewski, R., Stefanowicz-Rutkowska, M. M., Matuszewski, W., & Bandurska-Stankiewicz, E. M. (2022). Gestational Diabetes Mellitus-Recent Literature Review. Journal of Clinical Medicine, 11(19), 5736. https://doi.org/10.3390/jcm11195736

Negrato, C. A., & Zajdenverg, L. (2012). Self-monitoring of blood glucose during pregnancy: Indications and limitations. Diabetology & Metabolic syndrome, 4(1), 54. https://doi.org/10.1186/1758-5996-4-54

Nankervis, A., Price, S., & Conn, J. (2018). Gestational diabetes mellitus: A pragmatic approach to diagnosis and management. The Royal Australian College of General Practitioners, 47(7), 445-449. https://www1.racgp.org.au/ajgp/2018/july/gestational-diabetes-mellitus

Plows, J. F., Stanley, J. L., Baker, P. N., Reynolds, C. M., & Vickers, M. H. (2018). The Pathophysiology of Gestational Diabetes Mellitus. International Journal of Molecular Sciences, 19(11), 3342. https://doi.org/10.3390/ijms19113342