Gestational diabetes mellitus (GDM) is a type of diabetes that develops during pregnancy. It occurs when your body cannot produce enough insulin to meet the extra needs of pregnancy. This condition affects between 2% and 14% of pregnancies in the United States (1).
Table of Contents
What Is Gestational Diabetes?
Gestational diabetes is high blood sugar that starts during pregnancy. It usually develops between 24 and 28 weeks of pregnancy. During pregnancy, your placenta makes hormones that can make your body resistant to insulin. If your pancreas can’t make enough extra insulin to overcome this resistance, your blood sugar levels rise (2).
Unlike other types of diabetes, gestational diabetes usually goes away after your baby is born. However, having it increases your risk of developing type 2 diabetes later in life.
Symptoms
Most women with gestational diabetes don’t have noticeable symptoms. When symptoms do occur, they may include:
- Excessive thirst
- Frequent urination
- Fatigue
- Blurred vision
Because these symptoms can also be normal during pregnancy, gestational diabetes is usually found through routine screening rather than symptoms (3).
Who Is at Risk?
Several factors can increase your risk of developing gestational diabetes.
Weight and Body Mass Index
Being overweight or obese before pregnancy significantly increases your risk. Women who are overweight have almost twice the risk, while those with obesity have three times the risk. Women with severe obesity have more than five times the risk compared to women with normal weight (4).
Age
Women aged 25 and older have a higher risk. The risk increases by more than double for women over 25 years old (5).
Family History and Previous Pregnancy Complications
Your risk is higher if you have:
- A family history of diabetes (more than double the risk)
- Previous gestational diabetes (21 times higher risk)
- Previous stillbirth (more than double the risk)
- Previous baby weighing more than 9 pounds (2.5 times higher risk)
(5)
Other Medical Conditions
Women with polycystic ovary syndrome (PCOS) have about 20% of them developing gestational diabetes during pregnancy (6).
High iron levels may also increase risk. Women with higher ferritin levels (a marker of iron stores) have 58% higher odds of developing gestational diabetes. This is why routine iron supplementation should be carefully considered, especially if you already have adequate iron levels (7).
Race and Ethnicity
Some racial and ethnic groups have higher rates of gestational diabetes. In one large study, rates were highest among Asian American women (15.5%), followed by Hispanic women (9.0%) (8).
How Is Gestational Diabetes Diagnosed?
Most pregnant women are screened for gestational diabetes between 24 and 28 weeks of pregnancy. There are two main approaches to testing.
One-Step Test
In the one-step test, you fast overnight and then drink a solution with 75 grams of sugar. Your blood sugar is checked before drinking the solution, then at 1 hour and 2 hours after. You’re diagnosed with gestational diabetes if you have any of these values:
- Fasting: 92 mg/dL or higher
- 1 hour: 180 mg/dL or higher
- 2 hours: 153 mg/dL or higher
(3)
Two-Step Test
The two-step approach starts with a screening test where you drink 50 grams of sugar and have your blood checked after 1 hour. If this test is high, you come back for a longer test with 100 grams of sugar and blood checks over 3 hours.
Research shows that the one-step test diagnoses more women with gestational diabetes (11.5%) compared to the two-step test (4.9%), but doesn’t necessarily improve health outcomes (9).
Effects on Mother and Baby
Gestational diabetes can affect both you and your baby if not properly managed.
Effects on the Mother
Women with gestational diabetes have increased risks of:
- High blood pressure during pregnancy
- Cesarean delivery
- Type 2 diabetes after pregnancy (almost 10 times higher risk)
- Cardiovascular disease later in life
The risk of developing type 2 diabetes is particularly concerning. About 20% of women with gestational diabetes develop type 2 diabetes within 10 years, and this risk continues to increase over time (10).
Women with previous gestational diabetes also have a 74% higher risk of developing cardiovascular disease, including heart disease and stroke (11).
Effects on the Baby
Babies born to mothers with untreated gestational diabetes may have:
- Higher birth weight (macrosomia)
- Low blood sugar after birth
- Breathing problems (respiratory distress syndrome)
- Higher risk of stillbirth if diabetes is poorly controlled
- Preterm birth
- Higher risk of obesity and type 2 diabetes later in life
High blood sugar levels during pregnancy are continuously associated with increased birth weight and primary cesarean delivery. Even blood sugar levels below the typical diagnostic thresholds can increase these risks (12).
Treatment of gestational diabetes significantly reduces these risks. Studies show that treatment reduces serious complications for babies by 46% (13).
Treatment Options
The good news is that gestational diabetes can be effectively managed with proper treatment.
Lifestyle Changes
For many women, diet and exercise are enough to control blood sugar levels. These lifestyle changes are the first line of treatment.
Diet: Following a healthy eating plan is crucial. Low glycemic index diets (foods that don’t spike blood sugar quickly) can reduce the need for insulin and lower birth weight (14).
Important dietary considerations include:
- Choose whole grains over refined carbohydrates
- Include lean proteins with each meal
- Eat plenty of non-starchy vegetables
- Limit sugary foods and beverages
- Avoid alcohol completely during pregnancy
- Limit processed and ultra-processed foods
Research shows that women with gestational diabetes consume high amounts of processed and ultra-processed foods. In one study, 74% ate processed foods daily and 97% consumed ultra-processed foods daily. These foods can make blood sugar control more difficult (15).
Exercise: Regular physical activity helps control blood sugar. Studies show that exercise interventions reduce blood sugar levels after meals and help women meet their treatment goals (16).
The timing of exercise may not matter as much as simply being active. Research comparing short walks after meals versus one longer walk showed similar blood sugar control benefits. What’s most important is getting regular physical activity in whatever way works best for you (17).
Both aerobic exercise (like walking or swimming) and resistance training appear to be safe and beneficial. However, most studies have focused on aerobic exercise, so there’s more evidence for activities like walking. The most important thing is to find physical activities you enjoy and can do regularly (18).
Combined diet and exercise programs are particularly effective. They reduce the risk of cesarean delivery and babies being born too large. Women receiving these interventions also have a 29% lower risk of preterm birth (19, 20).
Blood Sugar Monitoring
You’ll need to check your blood sugar regularly, usually 4 times a day – when you wake up and after meals. Your healthcare team will teach you how to use a glucose meter and what your target levels should be.
Most doctors recommend keeping your blood sugar at these levels (13):
- Before meals: 95 mg/dL or less
- 1 hour after meals: 140 mg/dL or less
- 2 hours after meals: 120 mg/dL or less
Different doctors may recommend slightly different targets based on your individual situation. Some research suggests that tighter control (lower targets) may provide additional benefits (21).
Some women may use continuous glucose monitoring (CGM) devices that automatically track blood sugar throughout the day. While these devices can provide more data, research shows they may help achieve slightly better blood sugar control and lower weight gain compared to regular finger-stick monitoring (22).
Medications
If diet and exercise don’t control your blood sugar, you may need medication.
Insulin: This has been the traditional treatment and is very effective. It doesn’t cross the placenta, so it’s safe for your baby.
Oral medications: Some oral diabetes medications like metformin and glyburide can be used during pregnancy. Research shows they work about as well as insulin for most outcomes (23).
However, metformin appears to have some advantages over glyburide, including less maternal weight gain and lower risk of babies being too large (24).
Prevention of Gestational Diabetes
While not all cases can be prevented, there are ways to reduce your risk.
Before Pregnancy
If you’re planning to become pregnant:
- Achieve a healthy weight
- Start regular exercise
- Eat a balanced diet
During Pregnancy
Appropriate weight gain during pregnancy is important. Women who gain too much weight have a higher risk of gestational diabetes. Your doctor will recommend how much weight you should gain based on your pre-pregnancy weight.
Starting healthy habits early in pregnancy may help prevent gestational diabetes. Exercise interventions that begin before 15 weeks of pregnancy are more effective than those started later (25).
Diet and exercise programs during pregnancy can reduce the risk of gestational diabetes by about 15-23% overall. The most effective programs include (20):
- At least 150 minutes of moderate exercise per week
- Structured dietary advice focusing on healthy eating
- Regular weight monitoring
Special Considerations for High-Risk Women
For women at very high risk (such as those with PCOS or previous gestational diabetes), some doctors may recommend metformin during pregnancy to prevent GDM. Studies show this can reduce the risk by about 40% in high-risk women (26).
Delivery and Birth
Having gestational diabetes may affect your delivery plans. Your doctor will monitor your baby’s growth closely throughout pregnancy. If your baby is growing too large or if there are concerns about blood sugar control, your doctor may recommend inducing labor before your due date.
Research shows that treatment of gestational diabetes doesn’t increase the rate of induced labor significantly, suggesting that good blood sugar control allows many women to go into labor naturally (9).
After Pregnancy
Care doesn’t end when your baby is born. Follow-up is crucial for your long-term health.
Postpartum Testing
You should have your blood sugar tested 6-12 weeks after delivery to make sure it has returned to normal. This usually involves another glucose tolerance test. Some women may also benefit from early testing (before hospital discharge), though the 6-12 week test remains the most important (27).
Unfortunately, many women don’t get this important test. Studies show that postpartum screening rates vary widely, with some groups having rates as low as 33% (28).
Long-term Risk of Type 2 Diabetes
Having gestational diabetes significantly increases your risk of developing type 2 diabetes. Women with previous gestational diabetes have almost 10 times higher risk of developing type 2 diabetes compared to women who had normal pregnancies (29).
The risk is highest in the first few years after pregnancy but continues throughout life (10):
- 5 years after pregnancy: 16% develop type 2 diabetes
- 10 years: 20%
- 20 years: 29%
Reducing Your Risk
You can reduce your risk of developing type 2 diabetes by:
- Maintaining a healthy weight
- Continuing regular exercise
- Eating a healthy diet
- Getting regular diabetes screening
- Breastfeeding, which may help reduce risk
Recent research shows that lifestyle interventions after pregnancy can help prevent type 2 diabetes in women with previous gestational diabetes, though more studies are needed (30).
Living with Gestational Diabetes
Being diagnosed with gestational diabetes can feel overwhelming, but remember that with proper management, most women have healthy pregnancies and babies.
Daily Management Tips
- Eat regular, balanced meals and snacks
- Stay active with pregnancy-safe exercises like walking or swimming
- Monitor your blood sugar as directed
- Take medications as prescribed
- Attend all prenatal appointments
- Learn to count carbohydrates to better manage blood sugar
Managing Fasting Blood Sugar
Some women struggle with high morning blood sugar levels. Interestingly, research shows that eating a bedtime snack may actually increase fasting blood sugar the next morning. Women who skipped bedtime snacks had slightly lower morning blood sugar levels compared to those who ate snacks before bed (31).
If you’re having trouble with morning blood sugar levels, talk to your healthcare provider about whether bedtime snacks are right for you.
Emotional Support
It’s normal to feel anxious or worried about gestational diabetes. Talk to your healthcare team about your concerns. Consider joining a support group or connecting with other women who have had gestational diabetes.
When to Contact Your Healthcare Provider
Managing gestational diabetes requires regular communication with your healthcare team. Contact your provider if:
- Your blood sugar levels are consistently above target despite following your treatment plan
- Your blood sugar levels are too low (below 60 mg/dL)
- You feel dizzy, shaky, or confused (signs of low blood sugar)
- You’re unable to keep food down due to nausea or vomiting
- You have signs of infection (fever, burning during urination)
- You notice decreased fetal movement
- You have persistent headaches or vision changes
Regular prenatal visits are crucial when you have gestational diabetes. Your doctor will monitor your baby’s growth and may recommend additional tests to ensure your baby is healthy.
The Bottom Line
Gestational diabetes is a common pregnancy complication that requires careful management but usually resolves after delivery.
If you’re pregnant or planning to become pregnant, talk to your healthcare provider about your risk for gestational diabetes and what you can do to stay healthy. With proper care and management, you can have a healthy pregnancy and baby.