Gestational Diabetes: Symptoms, Causes & Treatment

What Is Gestational Diabetes?

Gestational diabetes mellitus (GDM) is a type of diabetes that develops during pregnancy when the body cannot produce enough insulin to meet the increased demands. It typically appears in the second or third trimester and affects 2-10% of pregnancies worldwide, depending on the population and diagnostic criteria used.

During pregnancy, the placenta produces hormones that help your baby develop and grow. However, these hormones can also block the action of insulin in your body, making your cells less sensitive to this essential hormone. This condition is called insulin resistance, and it means your body needs more insulin than usual to control blood sugar levels.

In most pregnancies, the pancreas compensates by producing extra insulin. However, in some women, the pancreas cannot keep up with the increased demand. When this happens, blood sugar levels rise above normal, resulting in gestational diabetes. The condition differs from having diabetes before pregnancy (pre-existing diabetes) and typically develops around weeks 24-28 when insulin resistance peaks.

Gestational diabetes is distinct from type 1 diabetes (an autoimmune condition) and type 2 diabetes (often related to lifestyle factors), though it shares some characteristics with type 2. After pregnancy, blood sugar levels usually return to normal. However, having gestational diabetes indicates that your body has difficulty managing insulin effectively, which increases your risk of developing type 2 diabetes later in life.

Why Does Gestational Diabetes Develop?

The placenta plays a crucial role in supporting your baby's growth, but it also produces hormones like human placental lactogen (hPL), estrogen, progesterone, and cortisol. These hormones are essential for fetal development but can interfere with insulin's ability to regulate blood sugar. This creates a natural insulin resistance during pregnancy.

Normally, the pancreas responds by producing up to three times more insulin than usual. In women who develop gestational diabetes, the beta cells in the pancreas cannot meet this increased demand. Contributing factors include genetics, pre-existing insulin resistance, and excess body weight, though gestational diabetes can occur in women without obvious risk factors.

What Are the Symptoms of Gestational Diabetes?

Gestational diabetes often has no noticeable symptoms, which is why routine screening during pregnancy is essential. When symptoms do occur, they may include increased thirst, frequent urination, fatigue, and blurred vision. Most cases are detected through blood tests rather than symptoms.

One of the challenging aspects of gestational diabetes is that it rarely causes obvious symptoms. Many of its potential signs, such as fatigue and frequent urination, are also common experiences during normal pregnancy. This overlap makes it nearly impossible to detect gestational diabetes based on symptoms alone, which is why prenatal screening is so important.

The body has a remarkable ability to adapt to moderately elevated blood sugar levels, often masking the condition. When blood sugar becomes significantly elevated, some women may experience symptoms, but by then the condition has typically been developing for some time. Early detection through routine testing allows for prompt treatment before complications can develop.

If you do experience symptoms, they typically appear gradually and may include the following:

• Increased thirst (polydipsia): Feeling unusually thirsty even when you've been drinking fluids regularly
• Frequent urination (polyuria): Needing to urinate more often, especially at night
• Unusual fatigue: Feeling more tired than expected, even with adequate rest
• Blurred vision: Temporary changes in vision due to fluid shifts in the lens
• Increased hunger: Feeling hungry more often, despite eating regular meals
• Recurrent infections: Particularly urinary tract infections or yeast infections

Why Symptoms Are Often Absent

The reason gestational diabetes frequently goes unnoticed is that mild to moderate elevations in blood sugar don't immediately affect how you feel. Your body compensates for these changes, and many pregnancy symptoms overlap with those of high blood sugar. This underscores the importance of attending all prenatal appointments and completing recommended screening tests.

What Causes Gestational Diabetes and Who Is at Risk?

Gestational diabetes is caused by the body's inability to produce enough insulin during pregnancy to overcome pregnancy-induced insulin resistance. Risk factors include being overweight, age over 25, family history of diabetes, previous gestational diabetes, and having previously given birth to a large baby.

The development of gestational diabetes involves a complex interaction between hormonal changes during pregnancy and your body's ability to respond to these changes. While any pregnant woman can develop the condition, certain factors significantly increase the risk. Understanding these risk factors helps healthcare providers identify women who may need earlier or more frequent screening.

Gestational diabetes has a genetic component. If close family members have type 2 diabetes, your risk of developing gestational diabetes increases. This suggests that some women inherit a tendency toward insulin resistance or reduced pancreatic function that becomes apparent during the metabolic stress of pregnancy.

Primary Risk Factors

Several factors significantly increase your likelihood of developing gestational diabetes:

• Overweight or obesity: Having a body mass index (BMI) of 25 or higher before pregnancy is one of the strongest risk factors
• Age over 25: Risk increases progressively with maternal age, though gestational diabetes can occur at any age
• Family history: Having a parent or sibling with type 2 diabetes increases your risk
• Previous gestational diabetes: If you had GDM in a previous pregnancy, there's a 30-50% chance of recurrence
• Previous large baby: Having given birth to a baby weighing more than 4.5 kg (10 lbs) suggests possible undiagnosed GDM
• Polycystic ovary syndrome (PCOS): This hormonal condition is associated with insulin resistance
• Certain ethnic backgrounds: Higher rates occur in women of South Asian, Middle Eastern, African, and Hispanic descent

How Is Gestational Diabetes Diagnosed?

Gestational diabetes is diagnosed through blood sugar tests during pregnancy, typically between weeks 24-28. The most common test is the oral glucose tolerance test (OGTT), where blood sugar is measured after fasting and after drinking a glucose solution. Some healthcare providers use a two-step approach with an initial glucose challenge test.

Screening for gestational diabetes is a standard part of prenatal care because the condition rarely causes symptoms. Different countries and healthcare systems may use slightly different testing protocols, but all aim to identify women whose blood sugar levels are above normal during pregnancy. Early detection allows for prompt treatment, which significantly improves outcomes for both mother and baby.

During routine prenatal visits, your healthcare provider may first perform simple blood tests. These can include a random blood glucose test or a fasting blood glucose test. If results suggest elevated blood sugar, or if you have risk factors for gestational diabetes, you'll be referred for more comprehensive testing.

The Oral Glucose Tolerance Test (OGTT)

The oral glucose tolerance test is the gold standard for diagnosing gestational diabetes. This test measures how well your body processes sugar and is typically performed between weeks 24 and 28 of pregnancy. Women with high-risk factors may be tested earlier, sometimes as early as weeks 10-12.

The test requires preparation and takes a few hours to complete:

• Fasting period: You'll need to fast overnight for 8-14 hours before the test (water is usually allowed)
• Baseline blood sample: A blood sample is taken to measure your fasting blood sugar level
• Glucose drink: You'll drink a solution containing 75 grams of glucose (sweet liquid)
• Follow-up blood samples: Blood is drawn at one hour and two hours after drinking the solution
• Result interpretation: Elevated readings at any point may indicate gestational diabetes

Two-Step Screening Approach

Some healthcare systems use a two-step process. First, a one-hour glucose challenge test (GCT) is performed, which doesn't require fasting. If this screening test is abnormal, you proceed to the full three-hour diagnostic OGTT. This approach may be more convenient but takes longer to reach a diagnosis.

How Is Gestational Diabetes Treated?

Treatment for gestational diabetes starts with dietary modifications and increased physical activity. If lifestyle changes alone don't control blood sugar levels, medication is added. Metformin tablets or insulin injections are safe and effective options during pregnancy. Regular blood sugar monitoring is essential to ensure good control.

The goal of treatment is to keep blood sugar levels within a target range that protects both mother and baby from complications. Treatment is highly individualized and depends on how high your blood sugar levels are and how well they respond to lifestyle modifications. Many women successfully manage gestational diabetes with diet and exercise alone, while others need additional medication.

Regardless of which treatment approach you need, regular monitoring and communication with your healthcare team are essential. Blood sugar levels can change throughout pregnancy, and treatment may need to be adjusted. With good management, most women with gestational diabetes have healthy pregnancies and deliver healthy babies.

Dietary Management

Diet is the cornerstone of gestational diabetes treatment. Working with a dietitian or diabetes educator can help you develop an eating plan that manages blood sugar while providing adequate nutrition for you and your growing baby. The focus is on balanced, regular meals with controlled carbohydrate intake.

Key dietary principles include:

• Regular meal timing: Eat three moderate meals and two to three snacks at consistent times
• Carbohydrate distribution: Spread carbohydrates evenly throughout the day rather than eating large amounts at once
• Choose complex carbohydrates: Focus on whole grains, vegetables, and legumes over refined starches and sugars
• Limit sugary foods: Avoid or minimize sweets, sugary drinks, and processed snacks
• Include protein and healthy fats: These slow down carbohydrate absorption and help stabilize blood sugar
• Control portion sizes: Even healthy foods can raise blood sugar if portions are too large

Physical Activity

Regular physical activity helps your body use insulin more effectively and can lower blood sugar levels. Most pregnant women with gestational diabetes can safely engage in moderate exercise, though it's important to discuss specific activities with your healthcare provider.

Recommended activities include walking, swimming, prenatal yoga, and light aerobics. Aim for at least 30 minutes of moderate activity on most days, though this can be broken into shorter sessions. Exercise after meals can be particularly helpful in controlling post-meal blood sugar spikes.

Medication Treatment

If diet and exercise don't bring blood sugar levels to target within one to two weeks, medication becomes necessary. This doesn't mean lifestyle efforts have failed - some women simply need additional help to maintain healthy blood sugar levels during pregnancy.

Metformin is often the first medication tried. This oral medication works by improving your body's sensitivity to insulin and reducing glucose production by the liver. It's generally safe during pregnancy and is taken with meals.

Insulin may be prescribed if metformin alone is insufficient or if blood sugar levels are significantly elevated. Insulin is given by injection and comes in several types with different durations of action. Your healthcare provider will teach you how to administer insulin safely and adjust doses based on your blood sugar readings.

How Is Gestational Diabetes Monitored?

Monitoring involves regular blood sugar testing at home (typically 4 times daily), more frequent prenatal visits, and additional ultrasound examinations to check your baby's growth. Self-monitoring helps you and your healthcare team adjust treatment to keep blood sugar in the target range.

Regular monitoring is essential for successful management of gestational diabetes. This involves tracking your blood sugar levels, attending more frequent medical appointments, and having additional tests to ensure your baby is developing well. Monitoring also helps identify if treatment adjustments are needed.

Blood sugar self-monitoring using a glucose meter is a key part of management. You'll typically test four or more times daily: fasting (before breakfast) and one to two hours after each main meal. Recording these values helps identify patterns and shows how different foods and activities affect your blood sugar.

Prenatal Monitoring

Women with gestational diabetes typically have more prenatal visits than those without the condition. These visits allow your healthcare team to review your blood sugar records, adjust treatment if needed, and monitor for complications. Key aspects of prenatal monitoring include:

• Regular ultrasounds: To check that your baby is growing appropriately and to estimate fetal weight
• Blood pressure monitoring: Gestational diabetes increases the risk of preeclampsia
• Fetal movement counts: You may be asked to track your baby's movements daily in the third trimester
• Non-stress tests: These may be performed in late pregnancy to check fetal well-being
• HbA1c testing: This blood test shows average blood sugar control over the past 2-3 months

What Complications Can Gestational Diabetes Cause?

Uncontrolled gestational diabetes can cause complications including macrosomia (large baby), increased risk of cesarean delivery, neonatal hypoglycemia (low blood sugar in newborn), preeclampsia, and increased long-term risk of type 2 diabetes for mother. With good blood sugar control, most complications can be prevented.

When blood sugar levels remain too high during pregnancy, it can affect both mother and baby. The good news is that most complications are directly related to poor blood sugar control, meaning that careful management significantly reduces these risks. Understanding potential complications helps motivate the lifestyle changes and treatment needed for good outcomes.

Complications for the Baby

High blood sugar in the mother means high blood sugar reaches the baby through the placenta. The baby's pancreas responds by producing extra insulin, which can lead to several complications:

• Macrosomia: Excess glucose and insulin promote growth, potentially resulting in a large baby (over 4 kg/9 lbs) that may complicate delivery
• Neonatal hypoglycemia: After birth, the baby may have low blood sugar because their pancreas is still producing extra insulin
• Respiratory distress: Babies of mothers with poorly controlled diabetes may have immature lungs
• Jaundice: Higher rates of newborn jaundice requiring treatment
• Future obesity and diabetes: Children exposed to high blood sugar in the womb have increased lifetime risks

Complications for the Mother

Gestational diabetes also poses risks to the mother's health, both during and after pregnancy:

• Preeclampsia: High blood pressure during pregnancy, which can be serious if untreated
• Cesarean delivery: Higher likelihood due to large baby size or other complications
• Polyhydramnios: Excess amniotic fluid, which can cause discomfort and preterm labor
• Type 2 diabetes: About 50% of women with gestational diabetes develop type 2 diabetes within 5-10 years
• Recurrent gestational diabetes: High likelihood of GDM in future pregnancies

What Happens After the Baby Is Born?

After delivery, blood sugar usually returns to normal as hormone levels normalize. Your baby's blood sugar will be monitored in the first hours after birth. You'll need a follow-up glucose tolerance test 6-12 weeks postpartum to confirm diabetes has resolved and regular screening thereafter to catch any development of type 2 diabetes early.

For most women with gestational diabetes, blood sugar levels return to normal within hours to days after delivery. Once the placenta is delivered, the hormones that caused insulin resistance rapidly decrease, and your body's insulin can work effectively again. However, the experience of gestational diabetes is an important indicator of your future metabolic health.

Immediate Postpartum Period

In the first 24-48 hours after birth, your baby's blood sugar will be monitored regularly. Because your baby produced extra insulin in response to high blood sugar during pregnancy, they may continue producing extra insulin temporarily, which can cause low blood sugar (hypoglycemia). Treatment is usually straightforward - extra breastmilk or formula feeding to maintain normal blood sugar levels.

If you were taking metformin or insulin during pregnancy, your healthcare provider will advise when to stop these medications. Most women can discontinue diabetes medications immediately after delivery, though some may need monitoring before this decision is made.

Follow-Up Testing

It's essential to have a glucose tolerance test 6-12 weeks after delivery to confirm your blood sugar has returned to normal. Approximately 5-10% of women with gestational diabetes will have persistent diabetes postpartum, usually type 2 diabetes. Early detection allows for prompt treatment to prevent complications.

Even if your postpartum test is normal, you'll need ongoing monitoring because of your increased lifetime risk of type 2 diabetes. Most guidelines recommend annual or biennial testing, depending on other risk factors. Maintaining awareness of this risk can motivate lifestyle habits that help prevent future diabetes.

How Can I Reduce My Risk of Gestational Diabetes?

While not all cases can be prevented, you can reduce your risk by maintaining a healthy weight before and during pregnancy, eating a balanced diet rich in fiber and whole foods, staying physically active, and avoiding excessive weight gain during pregnancy. These habits also reduce your risk of type 2 diabetes later in life.

Prevention begins before pregnancy when possible. If you're planning to become pregnant, achieving a healthy weight beforehand is one of the most effective ways to reduce your risk of gestational diabetes. Even modest weight loss can significantly improve your body's ability to use insulin effectively.

During pregnancy, focus on habits that support healthy blood sugar levels:

• Stay physically active: Regular moderate exercise improves insulin sensitivity and helps manage weight gain
• Follow a balanced diet: Emphasize vegetables, lean proteins, whole grains, and healthy fats while limiting refined sugars and processed foods
• Gain weight appropriately: Work with your healthcare provider to determine a healthy weight gain goal based on your pre-pregnancy weight
• Eat regular meals: Spread your food intake throughout the day rather than eating large meals
• Attend prenatal appointments: Regular monitoring allows for early detection and treatment if GDM does develop

After Gestational Diabetes: Long-Term Prevention

If you've had gestational diabetes, maintaining healthy habits after pregnancy is especially important. These same lifestyle factors that help prevent gestational diabetes also reduce your risk of developing type 2 diabetes later:

• Return to a healthy weight: Losing any excess weight gained during pregnancy reduces your future diabetes risk
• Continue regular exercise: Aim for at least 150 minutes of moderate activity per week
• Maintain healthy eating habits: The dietary principles that helped manage GDM are also excellent for long-term health
• Breastfeed if possible: Breastfeeding may help improve insulin sensitivity and assist with postpartum weight loss
• Get regular screening: Annual or biennial glucose testing allows for early detection if type 2 diabetes develops

What About Future Pregnancies?

If you've had gestational diabetes, there's a 30-50% chance of recurrence in future pregnancies. Before becoming pregnant again, ensure your blood sugar is well-controlled. Early testing and possibly earlier intervention can help manage GDM more effectively in subsequent pregnancies.

Having gestational diabetes in one pregnancy significantly increases your risk of developing it again. However, being aware of this risk means you and your healthcare team can take proactive steps to optimize your health before and during your next pregnancy.

Before conceiving again, schedule a preconception appointment to:

• Check current blood sugar levels: Ensure you don't have undiagnosed type 2 diabetes
• Achieve a healthy weight: If overweight, losing weight before pregnancy reduces recurrence risk
• Review medication history: Discuss any medications that may need adjustment before or during pregnancy
• Plan for early screening: You'll likely be tested for GDM earlier in future pregnancies