What You Need To Know About Gestational Diabetes

What is gestational diabetes?

Gestational diabetes (GDM) is when high blood sugar develops during pregnancy, typically mid-term. It usually disappears after giving birth. To be diagnosed with GDM, you must not have had diabetes before becoming pregnant.

GDM is typically a temporary condition. It can cause serious medical issues for the mother and baby during and after pregnancy.

Early diagnosis and optimal management are key to limiting the health impacts for you and your baby, as GDM can cause long-lasting effects for you both.

Once you receive a gestational diabetes diagnosis, immediately take your doctor’s advice. Implement lifestyle changes such as exercise and improvements in your diet to control your condition.

You will likely also require insulin or oral medication and need to monitor your blood sugars closely to prevent complications.


There was an incredible drop of 38% in the maternal mortality ratio¹ from 2000 to 2017. Still, one condition that increases maternal and fetal morbidity and mortality is on the rise.

Gestational diabetes mellitus (GDM) occurs in around 5–25.5% of pregnancies¹, although estimates vary based on geography. In some countries, it’s a major health issue: The Middle East and North Africa had the highest prevalence of GDM, with a median estimate of 12.9%.² Southeast Asia’s GDM prevalence is over 11%². Approximately 1 in 10 pregnant women in the US has diabetes³, most due to GDM. These numbers have been climbing along with the increase in obesity, more advanced maternal age, and even air pollution⁴.


Gestational diabetes rarely causes symptoms, so it’s crucial to keep up with all the screening offered during your pregnancy.

If you do experience symptoms, they may include:

  • Blurred vision

  • Fatigue

  • Frequent urination

  • Excessive thirst

  • Yeast infections

Complications of gestational diabetes

If gestational diabetes isn’t well-managed during your pregnancy, this can affect you and your baby. You may develop preeclampsia, which can be life-threatening, or you may need a C-section (cesarean section) to deliver your baby.

Your baby may be born with:

  • Breathing difficulties

  • Low blood sugar

  • Jaundice

  • A high birth weight

  • Prematurity

  • Shoulder dystocia, where your baby’s shoulders get stuck in your birth canal during labor

  • Birth trauma

  • Heart, facial, neurologic, and other congenital malformations

Infants born to mothers with untreated GDM have an increased risk of neonatal death¹ (within 28 days of birth) and long-term disability. They have a greater risk of obesity and developing type 2 diabetes later in life. Daughters of GDM-affected mothers are also more likely to be affected by GDM during any future pregnancy.

Women with prior GDM have a significantly increased risk for postpartum diabetes² and prediabetes. Studies have shown that a third of women who had GDM will develop type 2 diabetes³ within 15 years and up to 70% within 22–28 years⁴. These risks underscore the importance of long-term follow-up and screening⁵, so don’t forget to mention that you had GDM to your general physician in the years following your pregnancy.

If you have GDM, it is vital to:

  • Take your medication as prescribed.

  • Monitor your blood sugars closely.

  • Go to the recommended prenatal checks and ultrasounds throughout pregnancy.


While researchers don’t know what causes GDM exactly, they believe hormones play a role. Certain hormone levels increase to sustain your pregnancy. These include human placental lactogen (hPL) and other hormones that increase insulin resistance. This hormone boost is vital for a healthy pregnancy. However, it can make your body resistant to insulin, which regulates your blood sugar levels.

Insulin moves glucose into your cells from your blood. You naturally become more insulin resistant during pregnancy so your body can preserve glucose and carry it to your baby. However, if this resistance becomes too powerful, you can develop GDM, and your blood sugar levels rise abnormally because the insulin cannot do its job.

Who is at higher risk of developing gestational diabetes?

Researchers have discovered several risk factors for developing gestational diabetes. One study demonstrated an association of GDM with the following¹:

  • Maternal age over 35: The American Diabetic Association recommended a threshold of 25 years old, after which the risk increases. Other studies just pointed to a higher risk over age 35.

  • Being overweight or obese before the pregnancy

  • Family history of diabetes

  • History of GDM in a previous pregnancy

  • Smoking pre-pregnancy

  • Previously having a larger-than-average newborn

  • Previous stillbirth, miscarriage, or premature delivery

  • Being pregnant for the first time

The same study strongly recommended early GDM screening for all pregnant women, especially those at higher risk of GDM. Screening ensures early diagnosis and intervention to prevent complications.

Other risk factors include:

  • High blood pressure²

  • Gaining³ a large amount of weight during pregnancy if already overweight

  • Expecting multiple babies⁴ (i.e., twins, triplets)

  • Prescription steroid use (glucocorticoids)⁵

  • Polycystic ovary syndrome (PCOS)⁶ or other conditions associated with insulin resistance

  • Ancestry

A 2012 US study highlighted race and ethnicity-based risk⁷. The prevalence of GDM was highest among Filipinas and Asians at 10.9% and 10.2%, respectively. By comparison, non-Hispanic White and African-American rates were 4.5% and 4.4%.

These differences need further investigation, especially as the study only focused on women of different ethnic backgrounds living in the US. It does not include women currently living in their home countries. Growing evidence suggests that causes could include everything from body composition and lifestyle differences to healthcare systems. Obesity is a strong risk factor for GDM in all groups, especially among non-Asian racial/ethnic groups.

Geography also plays into risk. Many pregnancy-related conditions are more prevalent in low- and middle-income countries, and gestational diabetes is no different. These countries account for 88% of worldwide cases of diabetes in pregnancy⁸. High burden countries include India, China, Pakistan, Bangladesh, Indonesia, Nigeria, Brazil, and Mexico. The countries where GDM is most common are the least likely to offer screening and treatment. 

Diagnosis and testing for gestational diabetes

Screening is vital, and the earlier your physician catches and treats GDM, the better the outcome for you and your baby. Typically, you will receive screening during the highest risk period at 24–28 weeks. If you have risk factors, they will likely screen you earlier.

There are two tests doctors commonly use for gestational diabetes: A glucose challenge test and an oral glucose tolerance test (OGTT). They demonstrate how well your body uses glucose. Your doctor may do one of these tests or both. 

Glucose challenge test

Another name for this test is the glucose screening test, and it will usually be the first evaluation for most people. You don’t need to fast for this test.

A healthcare professional will give you a sweet drink containing glucose before drawing your blood an hour later for the glucose challenge test. If your blood glucose is 130–140 mg/dL or more, you may need an oral glucose tolerance test. If your blood glucose is 200 mg/dL or more, you may have diabetes.

Oral glucose tolerance test (OGTT)

Your healthcare professional may recommend going straight to the oral glucose tolerance test without the glucose challenge, particularly if you have risk factors.

The OGTT measures your blood glucose after fasting for at least eight hours. Your healthcare professional will first draw your blood for a baseline reading, and then you’ll drink the liquid containing a measured amount of glucose.

They will draw your blood every hour for 2–3 hours to check your blood sugar levels. You will be diagnosed with gestational diabetes if your test results show a high blood glucose level at any two or more test times. Your clinician will explain your OGTT results and the next steps.

Should I also be worried that I might already have type 2 diabetes?

The glucose challenge test at 24–28 weeks can pick up any type of diabetes. If you have certain risk factors, your doctor will likely test you for undiagnosed type 2 diabetes⁹ as early as your first prenatal appointment. These include:

  • Obesity or overweight

  • High blood pressure

  • Sedentary lifestyle

  • Family history of diabetes in a first-degree relative

  • History of prediabetes, gestational diabetes, or insulin resistance indicators (such as elevated hemoglobin A1C or polycystic ovarian syndrome)

  • Low levels of good cholesterol (HDL) 

  • High triglyceride levels 

  • Giving birth to a baby over 9lbs previously

  • African, Southeast Asian, Hispanic, Native American, Native Hawaiian, or Pacific Islander ancestry

Talk to your doctor if you have any concerns about your risk factors. They will be able to advise you on the best way to proceed.


There are two types of gestational diabetes, and their treatments are somewhat different. Both require you to monitor your blood sugar levels consistently. Your doctor will give or prescribe a glucose measuring device for you to use at home. 

Class A1

You can control this type of gestational diabetes through lifestyle modifications, primarily diet and exercise. Your diet¹ should be low in sugar, include plenty of whole fruits and vegetables, and contain moderate carbohydrates (up to 40%), protein (20%), and fat (40%). Eating regularly (three meals and two to three snacks) and remaining active can help you manage your blood glucose levels.

Guidelines² recommend exercising for 30 minutes at least three times a week. Your exercise regimen should include moderate-intensity cardiovascular and strength training. Walking for 10–15 minutes after meals³ and all forms of exercise can help your body utilize and regulate glucose. 

Class A2

If lifestyle modifications don’t improve your blood sugar levels, your healthcare clinician will treat you for class A2 GDM. This treatment involves insulin or oral³ medication. Doctors frequently prescribe metformin or glyburide, even though they have not been FDA-approved for this condition. Insulin is the first-line pharmacologic treatment as many who take oral medication still require insulin to achieve adequate blood sugar control.

After giving birth, your blood sugar levels should return to normal, but you are at higher risk of developing type 2 diabetes later in life. You should get tested for diabetes 4–12 weeks after delivery³ and then every 1–3 years afterward if those results are normal.

What diet should I follow if I have gestational diabetes?

Your diet is a really important part of dealing with gestational diabetes and keeping your blood sugar levels balanced. While many women may think they’re “eating for two,” only a slight increase in calories is necessary during pregnancy, usually about 300 calories a day⁴. The exact amount depends on your activity levels, prepregnancy weight, and if you are carrying more than one baby.

It is important to watch your caloric intake, but you should also pay close attention to the types of foods you consume. Here are some ways to include healthy foods in your diet:


Eating complex carbohydrates in moderation and spacing them out over your day is better for reducing blood sugar spikes. Your doctor will likely refer you to a dietician to ensure you cut your sugar intake while getting enough nutrients during your pregnancy. If they don’t, ask your doctor for a referral.

Healthy carbohydrate choices include:

  • All vegetables

  • Legumes: Beans, lentils, peas

  • Whole grains: Brown rice, oats, quinoa, bulgur wheat

  • Low-sugar fruits: Raspberries, kiwis, oranges, plums

Fiber is a type of carbohydrate. According to the American Heart Association⁵, you should aim for at least 25g a day. Getting enough fiber keeps your blood sugar down by slowing its absorption, giving your body a chance to respond to sugar hitting the bloodstream without requiring high insulin levels. Fiber-rich foods from plants also include healthy micronutrients, antioxidants, and anti-inflammatory compounds. There is no fiber in animal products. 


Two to three servings of protein daily are ideal during pregnancy. Proteins can originate from plant or animal sources.

Options include:

  • Poultry: Turkey, chicken, duck

  • Lean meats (low-fat cuts): Beef, pork, lamb

  • Fish: Cod, haddock, herring, salmon

  • Low-fat dairy products

  • Beans, lentils, tofu, tempeh, hummus, chia/flax/hemp seeds

The American College of Obstetricians and Gynecologists (ACOG) advises avoiding certain fish due to high mercury content⁶. These include:

  • Bigeye tuna

  • King mackerel

  • Marlin

  • Orange roughy

  • Shark

  • Swordfish

  • Tilefish (from the Gulf of Mexico)


Your body can only absorb vitamins A, D, E, and K with enough fat in your diet. Fats are also vital for fetal development, especially omega-3 fatty acids⁷. Consuming too much fat can lead to your baby being born with excess fat tissue, so it’s important to regulate your intake. It can also make it harder to control⁸ your gestational diabetes. Ask your doctor or dietician for advice on the best fat intake for you.

Healthy fat sources include:

  • Oily wild-caught fish

  • Avocado

  • Unsalted nuts and seeds (chia, hemp, flax, sunflower, sesame)

  • Eggs (make sure you fully cook them to avoid the risk of infection with Salmonella

Foods to avoid

This list looks like any other diet advice: Avoid highly processed foods. Anything with a lot of sugar is a huge no-no as it will spike your blood sugar. Foods to avoid include:

  • Alcoholic beverages

  • Baked goods, including donuts, cakes, and cookies

  • Fried or fast food

  • Potato chips

  • Candy

  • Sweetened “health” foods, like cereal, granola bars, flavored yogurt, and pre-sweetened, flavored oatmeal

  • Sugary drinks, including soda, sweetened beverages, and juice

  • Very starchy, processed foods, including white bread, white rice, and white pasta

Get used to checking food labels⁹. Sugar can be a sneaky ingredient with many different names on packaging. Ingredients ending in -ose are sugars, so they’re easy to check for. Look out for these other names for sugar: Glucose-fructose syrup, corn syrup, dextrose, fructose, maltose, honey, sucrose, lactose, invert sugar, cane sugar, fruit juice concentrates, glucose, syrup, and molasses.


While you can’t completely prevent gestational diabetes, you can assess yourself for the risk factors we’ve listed. Changing any of them before becoming pregnant, such as quitting smoking or losing weight, could substantially decrease your risk of developing GDM.

Whether or not you’re already pregnant, adopting a healthy, balanced diet and increasing your activity can decrease your diabetes risk. Speak to your doctor before making any big changes to your lifestyle while pregnant. Ensure you attend all your prenatal appointments, including screenings and evaluations. It’s important to keep on top of your prenatal care for your safety and your baby’s.

Clinical trials for gestational diabetes

Actively recruiting
Cardiovascular Disease & Type 2 Diabetes Study
Actively recruiting
Assessing an Investigational Medication on Major Adverse Cardiovascular Events Such as Heart Attack and Stroke
Actively recruiting
Heart Health Study