Gestational Diabetes

Gestational diabetes is a type of diabetes that develops during pregnancy and affects up to 9% of pregnancies in the United States each year. While it can be a concerning diagnosis, it’s treatable and manageable, and with proper care, most women deliver healthy babies.

Table of contents

• What is Gestational Diabetes?
• What Causes Gestational Diabetes?
• Who Is at Risk?
• Symptoms
• How It Can Affect Pregnancy and the Baby
• Screening and Testing
• Treatment and Management
• After Your Baby Is Born

What is Gestational Diabetes?

Gestational diabetes is a type of diabetes that develops exclusively during pregnancy when blood sugar levels become too high^[1]. The term gestational refers to pregnancy^[1]. Unlike other types of diabetes, gestational diabetes appears for the first time during pregnancy and typically goes away after the baby is born^[1].

This condition usually develops around the middle of pregnancy, typically between 24 and 28 weeks^[1]. It affects how the body’s cells use sugar, also called glucose, which is the body’s main source of energy^[1]. If you develop gestational diabetes, it doesn’t mean you had diabetes before pregnancy, nor does it necessarily mean you’ll have diabetes after giving birth^[2].

Gestational diabetes affects approximately 5% to 9% of pregnancies in the United States each year^[4]. The rate worldwide averages between 14% and 17%, though this can vary based on factors such as age, race and ethnicity, access to prenatal care, and geographic location^[3].

What Causes Gestational Diabetes?

Gestational diabetes develops because of hormonal changes during pregnancy and how your body converts food into energy^[3]. A hormone called insulin breaks down glucose from food and delivers it to your cells. Insulin keeps the level of glucose in your blood at a healthy level^[3].

During pregnancy, the placenta (the organ that connects the baby to the mother’s blood supply) produces hormones that support the baby’s growth^[2]. However, these hormones can sometimes block the mother’s insulin from working properly, leading to a condition called insulin resistance^[2]. This makes it harder for the body to use insulin effectively, requiring the mother to produce more insulin than usual^[2].

All pregnant women develop some insulin resistance during late pregnancy^[4]. However, if the body can’t produce enough insulin to meet this increased need, sugar builds up in the blood and leads to gestational diabetes^[2].

Who Is at Risk?

Anyone can develop gestational diabetes during pregnancy, but certain factors increase your risk^[3]. You’re at higher risk if you:

• Are over 40 years old^[6]
• Have a body mass index (BMI) above 30, meaning you are overweight or have obesity before pregnancy^[3][6]
• Previously had a baby who weighed more than 4.5 kg (10 pounds) at birth^[6]
• Had gestational diabetes in a previous pregnancy^[3][4]
• Have a parent or sibling with diabetes^[6]
• Are of South Asian, Black, African-Caribbean, or Middle Eastern origin (even if you were born in the UK)^[6]
• Are African American, Hispanic or Latino, American Indian, Alaska Native, Native Hawaiian, or Pacific Islander^[4]
• Have a hormone disorder called polycystic ovary syndrome (PCOS)^[4]
• Have high blood pressure or heart disease^[3]
• Have had a gastric bypass or other weight-loss surgery^[6]
• Are pregnant with twins or multiples^[7]

If any of these factors apply to you, you should be offered screening for gestational diabetes during your pregnancy^[6].

Symptoms

Gestational diabetes often doesn’t cause any symptoms that are easy to notice^[1]. Most cases are only discovered when blood sugar levels are tested during routine screening^[6]. This is why testing for gestational diabetes between 24 and 28 weeks of pregnancy is so important^[4].

If symptoms do occur, they may be mild and can include^[6]:

• Increased thirst
• Needing to urinate more often than usual
• A dry mouth
• Tiredness
• Blurred eyesight
• Genital itching or thrush

However, some of these symptoms are common during pregnancy and are not necessarily a sign of gestational diabetes^[6]. If you’re worried about any symptoms you’re experiencing, speak to your midwife or doctor^[6].

How It Can Affect Pregnancy and the Baby

High blood glucose levels during pregnancy can cause problems for both you and your baby^[5]. Fortunately, gestational diabetes is well understood, and healthcare providers are usually able to help you manage the condition with lifestyle and dietary changes^[3]. Most people don’t experience serious complications from gestational diabetes and deliver healthy babies^[3].

Potential effects on your baby include^[5]:

• Being born too early
• Weighing too much, which can make delivery difficult and may injure your baby
• Having low blood glucose (called hypoglycemia) right after birth
• Having breathing problems
• Developing yellowing of the skin and eyes (jaundice) after birth, which may require treatment^[6]

High blood glucose also can increase the chance of miscarriage or stillbirth (when the baby dies in the womb during the second half of pregnancy)^[5]. Your baby will also be more likely to become overweight and develop type 2 diabetes as he or she gets older^[5].

Potential effects on you include^[5][6]:

• Developing preeclampsia, a condition that causes high blood pressure and too much protein in your urine during the second half of pregnancy. This can cause serious or life-threatening problems for you and your baby
• Needing a cesarean section (C-section), which is major surgery, because your baby may be large
• Having too much amniotic fluid (the fluid that surrounds the baby) in the womb, called polyhydramnios, which can cause premature labor or problems at delivery
• Giving birth before the 37th week of pregnancy (premature birth)

If you have gestational diabetes, you are more likely to develop type 2 diabetes later in life^[5]. About half of women with gestational diabetes go on to develop type 2 diabetes^[4]. Over time, having too much glucose in your blood can cause health problems such as heart disease, kidney disease, and nerve damage^[5].

Screening and Testing

If possible, seek healthcare when you start to think about trying to get pregnant. Then your healthcare professional can check your risk of gestational diabetes and your overall wellness^[1]. Once you’re pregnant, your healthcare professional will check you for gestational diabetes as part of your prenatal care^[1].

During your first antenatal appointment (also called a booking appointment) at around week 8 to 12 of your pregnancy, your midwife or doctor will ask you some questions to determine whether you’re at an increased risk of gestational diabetes^[6]. If you have one or more risk factors, you should be offered a screening test^[6].

If you’re at average risk of gestational diabetes, you’ll likely have a screening test during the second trimester, typically between 24 and 28 weeks of pregnancy^[1]. If you’re at high risk, you may have the screening test earlier in pregnancy^[1]. If you’ve had gestational diabetes before, you’ll be offered a test earlier in your pregnancy, soon after your booking appointment, then another test at 24 to 28 weeks if the first test is normal^[6].

Initial glucose challenge test: You drink a syrupy glucose solution. One hour later, you have a blood test to measure your blood sugar level^[9]. A blood sugar level of 190 milligrams per deciliter (mg/dL), or 10.6 millimoles per liter (mmol/L), means you have gestational diabetes^[9]. A blood sugar level below 140 mg/dL (7.8 mmol/L) usually is thought to be within the standard range on a glucose challenge test^[9].

Follow-up glucose tolerance testing: If your blood sugar level is higher than expected on the initial test, you’ll need another glucose tolerance test^[9]. This test is like the first test, but the sweet drink has even more sugar^[9]. Your blood sugar is checked every hour for three hours^[9]. If two of the blood sugar readings are higher than expected, that means you have gestational diabetes^[9].

The screening test is called an oral glucose tolerance test (OGTT), which takes about 2 hours^[6]. It involves having a blood test in the morning when you have not had any food or drink for 8 to 10 hours (though you can usually drink water)^[6]. You’re then given a glucose drink. After resting for 2 hours, another blood sample is taken to see how your body is dealing with the glucose^[6].

Treatment and Management

If you have gestational diabetes, the chances of having problems with your pregnancy can be reduced by controlling your blood sugar levels^[6]. You can protect your own and your baby’s health by taking action right away to manage your blood glucose levels^[5].

Blood sugar monitoring: You’ll be given a testing kit that you can use to check your blood sugar level^[6]. This involves using a finger-pricking device and putting a drop of blood on a testing strip^[6]. You’ll usually be advised to test before breakfast and 1 hour after each meal^[6]. The American Diabetes Association suggests the following targets for most women with gestational diabetes: 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^[10].

Healthy eating: Making changes to your diet can help control your blood sugar levels^[6]. You should be referred to a dietitian, who can give you advice about your diet and how to plan healthy meals^[6]. The diet recommended for women with gestational diabetes should contain sufficient nutrients to support the growth of the baby and, at the same time, limit increases in blood sugar after meals and encourage appropriate weight gain^[12].

You may be advised to^[6]:

• Eat regularly (usually three meals a day) and avoid skipping meals
• Eat starchy and low glycemic index (GI) foods that release sugar slowly, such as wholewheat pasta, brown rice, granary bread, all-bran cereals, pulses, beans, lentils, muesli, and plain porridge
• Eat plenty of fruit and vegetables (aim for at least 5 portions a day)
• Avoid sugary foods (swap snacks such as cakes and biscuits for healthier alternatives such as fruit, nuts, and seeds)
• Avoid sugary drinks (diet or sugar-free drinks are better than sugary versions)
• Eat lean sources of protein, such as fish

Blood sugar excursions and high blood sugar episodes depend on carbohydrate intake. Therefore, nutritional counseling should focus on the type, amount, and distribution of carbohydrates in the diet^[12]. It’s important to measure your servings of starchy foods and limit portions. A reasonable serving size is about 1 cup of cooked rice, grain, noodles, or potatoes, or 2 pieces of bread, per meal^[15]. It’s best to limit milk to one cup at a time, and eat only one serving of fruit at a time^[15].

Physical activity: Physical activity lowers your blood glucose level, so regular exercise can be an effective way to manage gestational diabetes^[6]. You’ll be advised about safe ways to exercise during pregnancy^[6]. A common recommendation is to aim for at least 150 minutes (2 hours and 30 minutes) of moderate-intensity activity a week, plus strength exercises on 2 or more days a week^[6]. Gentle activities such as walking, swimming, and prenatal yoga can help reduce blood sugar^[6].

Medicine: You may be given medicine if your blood sugar levels are still not stable 1 to 2 weeks after changing your diet and exercising regularly, or if your blood sugar level is very high when you’re first diagnosed^[6]. This may be tablets (usually metformin) or insulin injections^[6]. Your blood sugar levels can increase as your pregnancy progresses, so even if they improve at first, you may need to take medicine later in pregnancy^[6]. You can usually stop taking these medicines after you give birth^[6].

Metformin is taken as a tablet up to 3 times a day, usually with or after meals^[6]. Side effects can include feeling sick, being sick, stomach cramps, diarrhea, and loss of appetite^[6]. Insulin may be recommended if you cannot take metformin or it causes side effects, if metformin does not lower your blood sugar levels enough, if you have very high blood sugar, or if your baby is very large^[6].

Increased monitoring: If you have gestational diabetes, you’ll need checkups more often^[1]. These extra checkups are most likely to be during the last three months of pregnancy^[1]. Your healthcare professional will check your blood sugar level and your baby’s health^[1]. You’ll also need to be more closely monitored during pregnancy and labor to check if treatment is working and for any problems^[6].

After Your Baby Is Born

For most people who have gestational diabetes, blood sugar goes back to its usual level soon after a baby is born^[1]. However, if you’ve had gestational diabetes, you have a higher risk of getting type 2 diabetes^[1]. That means you’ll need to be tested for changes in blood sugar more often^[1].

Talk to your doctor about how to lower your risk of developing type 2 diabetes^[4]. You can take steps to help prevent or delay type 2 diabetes^[5]. Ask how often to have your blood sugar checked to make sure you’re on track^[4].