Diabetes mellitus is a group of diseases marked by high blood sugar, and gestational diabetes is one type of diabetes that develops during pregnancy due to hormonal changes.
Causes and Risk Factors of Gestational Diabetes
Similar to type 2 diabetes, gestational diabetes develops when the body is no longer able to respond effectively to insulin — a condition called insulin resistance.
When the body's cells don't properly absorb glucose, the simple sugar builds up in the bloodstream, resulting in elevated levels of glucose on blood tests.
“Gestational diabetes is caused by the effects of placental hormones,” says Kevin Borst, DO, an endocrinologist at Cleveland Clinic in Ohio. “These can increase insulin resistance in susceptible individuals. It is not fully understood why some women don’t tolerate these hormones well and ultimately develop gestational diabetes.”
These hormones include:
- Growth hormones
- Cortisol (a stress hormone)
- Estrogen and progesterone
- Human placental lactogen (a hormone produced in the placenta that helps break down fat from the mother to provide energy for the fetus)
- Placental insulinase (another hormone from the placenta that inactivates insulin)
What's more, other changes during pregnancy — such as eating more, exercising less, and having larger fat deposits — can contribute to insulin resistance.
- Prediabetes (blood sugar that's elevated, but not high enough to be called diabetes)
- High blood pressure
- A personal or family history of gestational diabetes
- A family history of type 2 diabetes
- Hormone disorders, such as polycystic ovary syndrome (PCOS)
- Being overweight, or gaining too much weight during pregnancy
- Being older than 25
- Being of African, American Indian, Asian, Hispanic, or Pacific Islander descent
- Previously giving birth to a baby that weighed at least 9 pounds or had a birth defect
- Previously having an unexplained stillbirth or miscarriage
Still, some women without any of these risk factors may go on to develop gestational diabetes due to their intolerance of the placental hormones, Dr. Borst explains.
How Is Gestational Diabetes Diagnosed?
Screening tests for gestational diabetes include:
Glucose Challenge Test This test involves drinking a syrupy glucose solution, and then undergoing blood test to measure your blood sugar level one hour later. Generally, a blood sugar level is considered normal if it is below 140 milligrams per deciliter (mg/dL) or 7.8 millimoles per liter (mmol/L), according to the Mayo Clinic. A blood sugar level of 190 mg/dL or 10.6 mg/dL indicates gestational diabetes.
Follow-Up Glucose Testing If your blood sugar level was higher than normal during the initial glucose challenge test, you’ll need to complete another one to determine if you have gestational diabetes. This test will be similar to the first screening except the glucose solution will be sweeter and your blood will be checked hourly for three hours. If two of these blood tests come back high, you will receive a gestational diabetes diagnosis.
Prognosis of Gestational Diabetes
However, women who have had gestational diabetes are at an increased risk of getting it again during future pregnancies and are also at an increased risk of type 2 diabetes later in life. For this reason, it’s important for women who have had gestational diabetes to have their blood glucose levels regularly checked even after pregnancy.
Treatment and Medication Options for Gestational Diabetes
Gestational diabetes can be managed with close blood sugar monitoring, lifestyle changes, and in some cases, medication.
Monitor your blood sugar. If you have gestational diabetes, your doctor may ask you to monitor your blood sugar levels several times a day.
- Before a meal: 95 mg/dL or less
- One hour after a meal: 140 mg/dL or less
- Two hours after a meal: 120 mg/dL or less
Maintain a healthy diet. “Unfortunately, gestational diabetes will not go away while still pregnant, because all those metabolic changes are still occurring that drive the insulin resistance,” Fay explains. “However, it can sometimes be controlled with diet alone.”
She typically recommends a diet of 30 to 40 percent carbohydrates, and choosing those carbohydrates that are more slowly digested and less likely to cause blood sugar spikes. These foods tend to be high in fiber. “For example, having whole wheat bread instead of white bread, or having whole fruit instead of fruit juice,” Fay says. A certified diabetes care and education specialist and registered dietitian nutritionist, which you can find via the Association of Diabetes Care and Education Specialists, can help you build a diabetes-friendly diet.
Get exercise. Talk to your doctor about the amount and level of physical activity that is right for you during your pregnancy. Faye typically recommends 30 minutes of exercise at least five days a week for all her patients. “Adding in a walk after meals can also help lower blood sugars,” she says.
6 Great Exercises for People With Diabetes
Use medication. Sometimes, lifestyle changes may not be enough to manage gestational diabetes sufficiently. “If blood sugars remain elevated despite modifications in diet, the treatment for gestational diabetes is use of insulin,” Borst says. “This is safe and effective in pregnancy.”
Your healthcare provider will teach you how to use a small needle to give yourself insulin shots. Some doctors may prescribe a different medication to take orally.
Prevention of Gestational Diabetes
While there is no guaranteed way to prevent gestational diabetes, there are some steps you can take to lower your risk.
“The best way to reduce your risk of developing gestational diabetes is to maintain a proper diet and body weight prior to and during the pregnancy, as well as increasing physical activity,” Borst says.
Focus your diet on healthy foods that are high in fiber and low in fat like fruits, vegetables, and whole grains. Try to get at least 30 minutes of moderate physical activity each day. These healthy habits can make lasting changes that will help you through your pregnancy.
“However, sometimes women who are of normal weight, who exercise and have a healthy diet, still may develop gestational diabetes,” Fay says. In these cases, it is likely to occur because of the effects of placental hormones. Genetics may also play a role, as there is a higher risk of gestational diabetes in patients who have a first-degree relative (such as a mother or father) with diabetes, Fay says.
Research and Statistics: How Many People Have Gestational Diabetes?
Related Conditions and Causes of Gestational Diabetes
Many people may not realize that type 1 diabetes, type 2 diabetes, and gestational diabetes are different kinds of diabetes.
As previously mentioned, gestational diabetes is caused by the effects of placental hormones and develops only in pregnant women who didn't have diabetes before becoming pregnant.
Type 1 Diabetes is when the pancreas doesn’t produce insulin or makes very little insulin. It is believed to be caused by an immune reaction and can’t yet be prevented. Type 1 diabetes occurs most often in children, teens, and young adults and often starts quickly and has severe symptoms. People with type 1 diabetes need to use insulin daily.
Type 2 Diabetes comes on gradually, developing over many years. It can be prevented or delayed with lifestyle changes, such as maintaining a healthy weight, exercising, and eating a healthy diet. Type 2 diabetes mainly occurs in older adults, although kids, teenagers, and younger adults can develop it, as well.
Conditions that may increase the risk of gestational diabetes include obesity and PCOS.
Gestational Diabetes Resources We Love
Favorite Orgs for Essential Info on Gestational Diabetes
American Diabetes Association (ADA)
The ADA is considered the leading nonprofit for diabetes education. Get tips on diet, exercise, and healthy habits to help manage gestational diabetes, and join the online community to connect with others who are going through similar experiences.
The American College of Obstetricians and Gynecologists (ACOG)
ACOG is the leading group of obstetricians and gynecologists dedicated to improving women’s health. Learn about ways to manage gestational diabetes, how to track blood sugar levels, and steps you can take to have a healthy pregnancy from the experts who diagnose and treat the condition every day.
Women With Gestational Diabetes
This project from the International Diabetes Federation (IDF), an umbrella organization of more than 240 diabetes associations in 168 countries, offers articles, as well as video guides on insulin, healthy eating, and blood glucose monitoring. You can also test your knowledge with interactive quizzes on topics such as how to reduce your risk and how to manage gestational diabetes with diet and exercise.
Favorite Gestational Diabetes Support Group
What to Expect Gestational Diabetes Forum
What to Expect is a nationally leading and trusted source on all things pregnancy and parenting, and a partner site of Everyday Health. On this message board, connect with other women who are living with gestational diabetes and share your diet plans and other tips for staying healthy during pregnancy.
Favorite App for Gestational Diabetes
This app acts as a reliable companion to aid management of gestational diabetes. It can help you analyze dips and rises in your blood sugar readings, offers education about blood sugar management, and facilitates connecting you virtually with a certified diabetes care and education specialist. MySugr is free on Android and iOS with in-app purchases available.
For more of our favorite diabetes apps, check out our list.
Favorite Resource for Becoming an Advocate
International Diabetes Federation (IDF)
Want to get involved and help others with gestational or other types of diabetes? Consider checking out the IDF’s advocacy network page, where you can find different organizations to work with to help increase diabetes-related research, legislation, and awareness.
Editorial Sources and Fact-Checking
- Gestational Diabetes. National Institute of Diabetes and Digestive and Kidney Diseases.
- Gestational Diabetes. Harvard Health Publishing. April 2019.
- Gestational Diabetes. Stanford Children’s Health.
- Gestational Diabetes Mellitus (GDM). Johns Hopkins Medicine.
- Gestational Diabetes. Mayo Clinic. August 26, 2020.
- Gestational Diabetes and a Healthy Baby? Yes. American Diabetes Association.
- Diabetes During Pregnancy. Centers for Disease Control and Prevention. June 12, 2018.
- Gestational Diabetes FAQ. American College of Obstetricians and Gynecologists. October 2020.
- Gestational Diabetes and Pregnancy. Centers for Disease Control and Prevention. July 14, 2020.
- Disparities in the Risk of Gestational Diabetes by Race-Ethnicity and Country of Birth. Paediatric and Perinatal Epidemiology. October 1, 2014.
- Racial/Ethnic Differences in Diabetes Screening and Hyperglycemia Among US Women After Gestational Diabetes. CDC Preventing Chronic Disease. October 24, 2019.
- The Surprising Truth About Prediabetes. Centers for Disease Control and Prevention. June 11, 2020.
- Prediabetes. Mayo Clinic. September 22, 2020.
- Obesity and Pregnancy. The American College of Obstetricians and Gynecologists Obesity and Pregnancy. May 2019.
- PCOS (Polycystic Ovary Syndrome) and Diabetes. Centers for Disease Control and Prevention. March 24, 2020.
- Silverman M, Reichenberg A, Savitz D, et al. The Risk Factors for Post Part Depression: A Population-Based. Depression and Anxiety. February 2017.