Gestational Diabetes Mellitus (GDM)

Gestational diabetes, also known as gestational diabetes mellitus (GDM), is a sub-type of diabetes that is first identified during pregnancy. It consists of abnormal glucose tolerance or higher-than-normal blood glucose levels, which may or may not diminish following the birth of an infant. The prevalence of GDM in Canada has been on the increase, with approximately 5% of Canadian pregnancies in 2010/2011 reported to be affected by GDM. Although GDM is usually asymptomatic (shows no symptoms), it is associated with serious perinatal complications for both the mother and the child. However, with early detection and management, these complications can be minimized.

Impact of GDM on Maternal and Infant Health

Mothers with GDM are at risk of a wide range of health issues during pregnancy, delivery, and postpartum. These risks include, but are not limited to:

Pre-eclampsia (a form of hypertension in pregnancy characterized by protein in urine)
Delivery of a macrosomic infant (large for gestational age) associated with delivery risks such as:
- prolonged labour
- the need for instrumental delivery (e.g., use of forceps) and unplanned caesarean section
- preterm birth and increased risk of postpartum hemorrhage
- maternal birth injuries (e.g., risk of laceration and tear of vaginal tissue)
- genital tract injury and uterine atony (the inability of the uterus muscle to properly contract)
Post-pregnancy type 2 diabetes
Maternal death

Babies born to mothers with GDM are also at risk for:

Macrosomia (i.e., birth weight greater than 4 kilograms)
Neonatal hypoglycemia (low blood sugar in the newborn)
Perinatal death and stillbirth
Type 2 diabetes (in children, youth, and adults)
Autism spectrum disorders
Obesity and being overweight later in life
Cardiovascular disease later in life

Risk Factors for GDM

Certain risk factors may increase the likelihood of a woman developing GDM during her pregnancy. Having one or more of these risk factors does not guarantee a GDM diagnosis, but rather suggests a need for GDM screening during pregnancy. These risk factors include:

Polycystic ovary syndrome (PCOS)
Genetics or family history of diabetes
Women aged 35 years and older
Women pregnant with a male fetus
Previous macrosomia
Previous GDM diagnosis
Ethnicity – In Canada, First Nations women are the most at risk. Women from other ethnicities (South and Southeast Asian, Pacific Island, African, and Latin American) may also be at higher risk, especially if they were born outside of Canada.

Behavioural factors can also play a role in the development of GDM. Behavioural risk factors include:

Insufficient sleep duration and poor sleep quality
Obesity and weight gain
Unhealthy food (i.e., high intake of red and processed meats, saturated fats, refined grains, sweets, high-fat dairy, and fried foods)
Vitamin D deficiency
Deficiency of iron from non-heme sources such as vegetables, fruits, legumes, and nuts
Cigarette smoking

Adjusting these behaviours before or during pregnancy may decrease the chances of developing GDM, or limit the effects of GDM, on the mother’s and child’s health.

Polycystic ovary syndrome (PCOS) is a type of hormonal disorder common among women of reproductive age. It can cause problems with menstrual periods and make it difficult to get pregnant.

Screening and Diagnosis

GDM can be diagnosed at any point during a pregnancy. However, the typical time frame of diagnosis is between 24 and 28 weeks of gestation. Although a variety of screening methods have been used, the glucose challenge test (GCT) and the fasting plasma glucose (FPG) test are believed to be the best predictors of GDM. The World Health Organization (WHO) also recommends utilizing the oral glucose tolerance test (OGTT); a test that measures the ability of the body to use glucose (the body’s main source of energy).

Diabetes Canada recommends a preferred and an alternative approach for the screening and diagnosis of GDM. The preferred approach involves using 50 g GCT and/or 75 g OGTT, while the alternative approach uses only the 75 g OGTT (Diabetes Canada Clinical Practice Guidelines Expert Committee, 2018). Both the GCT and OGTT involve drinking a sweet liquid containing a measured amount of glucose, after which blood samples are collected at timed intervals usually one or two hours after drinking the liquid. For more information on the screening and diagnosis of GDM, please visit: Screening and Diagnosis for Gestational Diabetes.

Management of GDM

Most women diagnosed with GDM can be helped to effectively manage their glucose levels through lifestyle interventions comprising dietary counselling, encouragement of physical activity, and monitoring of blood glucose levels. For women who do not achieve target glucose levels within two weeks of initiating lifestyle modifications, glucose lowering therapy of insulin may be prescribed.

Dietary Intervention

Even though there is no universal dietary recommendation that applies to all women with GDM, some researchers propose a daily caloric intake and distribution model based on the American Diabetes Association’s recommendations for managing type 2 diabetes. The recommendations incorporate dietary needs for fetal development; specifically, the need for additional carbohydrates that promote fetal brain development. Similarly, Diabetes Canada suggests some dietary recommendations for GDM, which can be found here: Gestational Diabetes Diet.

Physical Activity

Exercise is part of a healthy pregnancy and may provide additional benefits for women diagnosed with GDM. Pregnant women who exercise throughout their pregnancy may experience benefits such as:

Improved physical condition
Control of body weight
Shorter duration of labour
Quicker recovery after birth
Prevention of health conditions (including GDM)
Reduced risk of premature birth

The Society of Obstetricians and Gynecologists of Canada (SOGC) suggests that women with GDM follow the same physical activity guidelines as other pregnant women. Some exercise recommendations include aerobic exercises three to four times a week (e.g., walking, jogging, running), along with resistance, weight-bearing, flexibility-balance, and stretch exercises (e.g., yoga, pilates, tai chi). Specifically, 20-30 minutes of moderate-intensity exercise per day is believed to lower glucose levels in women with GDM. For more recommendations on physical activity during pregnancy, visit: Physical Activity and Exercise During Pregnancy and the Postpartum Period.

Prevention of GDM

Certain protective factors can help to prevent the development of GDM. These include:

Physical activity
Mothers who are experiencing a pregnancy without contraindications (i.e., a low-risk pregnancy) should continue or begin a physical activity routine that includes 150 minutes of moderate-intensity exercise each week to achieve reductions in pregnancy complications such as GDM.
Sleep
Pregnant women should aim for 8-9 hours of quality sleep, as well as be monitored for disordered sleeping patterns throughout their pregnancy. For women who achieve less than 7 hours of sleep, short uninterrupted daytime naps may be of benefit.
Nutrition
At-risk women are encouraged to consume vegetables, fruits, plant proteins, and lean meats to reduce the likelihood of developing GDM.
Probiotic-rich products
Probiotics are live microorganisms that help to improve or restore gut flora. When probiotic-rich products (e.g., yogurt) are consumed in adequate amounts, they may help to improve glucose control in pregnant women and decrease the rates of GDM in at-risk women.

Additional Resources

External links

Gestational Diabetes Mellitus (GDM)

Gestational diabetes, also known as gestational diabetes mellitus (GDM), is a sub-type of diabetes that is first identified during pregnancy. It consists of abnormal glucose tolerance or higher-than-normal blood glucose levels, which may or may not diminish following the birth of an infant. The prevalence of GDM in Canada has been on the increase, with approximately 5% of Canadian pregnancies in 2010/2011 reported to be affected by GDM. Although GDM is usually asymptomatic (shows no symptoms), it is associated with serious perinatal complications for both the mother and the child. However, with early detection and management, these complications can be minimized.

Impact of GDM on Maternal and Infant Health

Mothers with GDM are at risk of a wide range of health issues during pregnancy, delivery, and postpartum. These risks include, but are not limited to:

Pre-eclampsia (a form of hypertension in pregnancy characterized by protein in urine)
Delivery of a macrosomic infant (large for gestational age) associated with delivery risks such as:
- prolonged labour
- the need for instrumental delivery (e.g., use of forceps) and unplanned caesarean section
- preterm birth and increased risk of postpartum hemorrhage
- maternal birth injuries (e.g., risk of laceration and tear of vaginal tissue)
- genital tract injury and uterine atony (the inability of the uterus muscle to properly contract)
Post-pregnancy type 2 diabetes
Maternal death

Babies born to mothers with GDM are also at risk for:

Macrosomia (i.e., birth weight greater than 4 kilograms)
Neonatal hypoglycemia (low blood sugar in the newborn)
Perinatal death and stillbirth
Type 2 diabetes (in children, youth, and adults)
Autism spectrum disorders
Obesity and being overweight later in life
Cardiovascular disease later in life

Risk Factors for GDM

Certain risk factors may increase the likelihood of a woman developing GDM during her pregnancy. Having one or more of these risk factors does not guarantee a GDM diagnosis, but rather suggests a need for GDM screening during pregnancy. These risk factors include:

Polycystic ovary syndrome (PCOS)
Genetics or family history of diabetes
Women aged 35 years and older
Women pregnant with a male fetus
Previous macrosomia
Previous GDM diagnosis
Ethnicity – In Canada, First Nations women are the most at risk. Women from other ethnicities (South and Southeast Asian, Pacific Island, African, and Latin American) may also be at higher risk, especially if they were born outside of Canada.

Behavioural factors can also play a role in the development of GDM. Behavioural risk factors include:

Insufficient sleep duration and poor sleep quality
Obesity and weight gain
Unhealthy food (i.e., high intake of red and processed meats, saturated fats, refined grains, sweets, high-fat dairy, and fried foods)
Vitamin D deficiency
Deficiency of iron from non-heme sources such as vegetables, fruits, legumes, and nuts
Cigarette smoking

Adjusting these behaviours before or during pregnancy may decrease the chances of developing GDM, or limit the effects of GDM, on the mother’s and child’s health.

Screening and Diagnosis

GDM can be diagnosed at any point during a pregnancy. However, the typical time frame of diagnosis is between 24 and 28 weeks of gestation. Although a variety of screening methods have been used, the glucose challenge test (GCT) and the fasting plasma glucose (FPG) test are believed to be the best predictors of GDM. The World Health Organization (WHO) also recommends utilizing the oral glucose tolerance test (OGTT); a test that measures the ability of the body to use glucose (the body’s main source of energy).

Diabetes Canada recommends a preferred and an alternative approach for the screening and diagnosis of GDM. The preferred approach involves using 50 g GCT and/or 75 g OGTT, while the alternative approach uses only the 75 g OGTT (Diabetes Canada Clinical Practice Guidelines Expert Committee, 2018). Both the GCT and OGTT involve drinking a sweet liquid containing a measured amount of glucose, after which blood samples are collected at timed intervals usually one or two hours after drinking the liquid. For more information on the screening and diagnosis of GDM, please visit: Screening and Diagnosis for Gestational Diabetes.

Management of GDM

Most women diagnosed with GDM can be helped to effectively manage their glucose levels through lifestyle interventions comprising dietary counselling, encouragement of physical activity, and monitoring of blood glucose levels. For women who do not achieve target glucose levels within two weeks of initiating lifestyle modifications, glucose lowering therapy of insulin may be prescribed.

Dietary Intervention

Even though there is no universal dietary recommendation that applies to all women with GDM, some researchers propose a daily caloric intake and distribution model based on the American Diabetes Association’s recommendations for managing type 2 diabetes. The recommendations incorporate dietary needs for fetal development; specifically, the need for additional carbohydrates that promote fetal brain development. Similarly, Diabetes Canada suggests some dietary recommendations for GDM, which can be found here: Gestational Diabetes Diet.

Physical Activity

Exercise is part of a healthy pregnancy and may provide additional benefits for women diagnosed with GDM. Pregnant women who exercise throughout their pregnancy may experience benefits such as:

Improved physical condition
Control of body weight
Shorter duration of labour
Quicker recovery after birth
Prevention of health conditions (including GDM)
Reduced risk of premature birth

The Society of Obstetricians and Gynecologists of Canada (SOGC) suggests that women with GDM follow the same physical activity guidelines as other pregnant women. Some exercise recommendations include aerobic exercises three to four times a week (e.g., walking, jogging, running), along with resistance, weight-bearing, flexibility-balance, and stretch exercises (e.g., yoga, pilates, tai chi). Specifically, 20-30 minutes of moderate-intensity exercise per day is believed to lower glucose levels in women with GDM. For more recommendations on physical activity during pregnancy, visit: Physical Activity and Exercise During Pregnancy and the Postpartum Period.

Prevention of GDM

Certain protective factors can help to prevent the development of GDM. These include:

Physical activity
Mothers who are experiencing a pregnancy without contraindications (i.e., a low-risk pregnancy) should continue or begin a physical activity routine that includes 150 minutes of moderate-intensity exercise each week to achieve reductions in pregnancy complications such as GDM.
Sleep
Pregnant women should aim for 8-9 hours of quality sleep, as well as be monitored for disordered sleeping patterns throughout their pregnancy. For women who achieve less than 7 hours of sleep, short uninterrupted daytime naps may be of benefit.
Nutrition
At-risk women are encouraged to consume vegetables, fruits, plant proteins, and lean meats to reduce the likelihood of developing GDM.
Probiotic-rich products
Probiotics are live microorganisms that help to improve or restore gut flora. When probiotic-rich products (e.g., yogurt) are consumed in adequate amounts, they may help to improve glucose control in pregnant women and decrease the rates of GDM in at-risk women.

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Gestational Diabetes Mellitus (GDM)

Impact of GDM on Maternal and Infant Health

Risk Factors for GDM

Screening and Diagnosis

Management of GDM

Dietary Intervention

Physical Activity

Prevention of GDM

Additional Resources

External links

Gestational Diabetes Mellitus (GDM)

Impact of GDM on Maternal and Infant Health

Risk Factors for GDM

Screening and Diagnosis

Management of GDM

Dietary Intervention

Physical Activity

Prevention of GDM

Additional Resources

External links