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Understanding
Gestational Diabetes

A Complete Guide for You and Your Baby

You have been diagnosed with gestational diabetes. This guide will help you understand what it means, what to do, and how to protect your baby.

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How Common Is Gestational Diabetes?

You are not alone — this is one of the most common pregnancy complications

1 in 10

Pregnancies in the U.S. are affected by GDM

50–70%

Of women with GDM develop Type 2 Diabetes within 10 years

76%

Higher risk of GDM recurring in a future pregnancy

GDM is manageable. With the right care, most women with GDM have healthy pregnancies and healthy babies.

What Is Gestational Diabetes?

The Simple Explanation

During pregnancy, the placenta makes hormones that block insulin from working properly.

Your pancreas cannot keep up, so blood sugar rises above the safe range.

It Is Not Your Fault

GDM is caused by placental hormones — not by anything you ate or did wrong.

It typically resolves after delivery when the placenta is delivered.

GDM is usually diagnosed between 24–28 weeks, when placental hormone levels peak.

How Is GDM Diagnosed?

ACOG recommends universal screening at 24–28 weeks

Step 1: 1-Hour Glucose Challenge

Drink a 50g glucose solution. Blood drawn 1 hour later.

If ≥ 130–140 mg/dL → proceed to Step 2

No fasting required for this test.

Step 2: 3-Hour Glucose Tolerance Test

Fasting + 100g glucose. Blood drawn at 1, 2, and 3 hours.

GDM diagnosed if 2 or more values exceed thresholds

Fasting required for this test.

Some providers use a one-step approach: a 2-hour 75g test (fasting required). Your provider will tell you which test you had.

Who Is at Higher Risk?

Risk factors help identify who needs earlier or more frequent screening

  • BMI ≥ 25 (overweight) or ≥ 30 (obese)
  • Previous gestational diabetes
  • Family history of Type 2 Diabetes
  • Prior baby weighing more than 9 lbs
  • Polycystic ovary syndrome (PCOS)
  • Age 35 or older
  • Hispanic, Black, Asian, or Pacific Islander ancestry
  • Prediabetes before pregnancy
  • Physical inactivity
  • Multiple gestation (twins or more)

Having risk factors does not mean you will develop GDM. Many women with no risk factors are also diagnosed. Screening is recommended for all pregnant women.

Understanding Your GDM Classification

Not all GDM is the same — your type guides your treatment plan

A1

A1GDM — Diet-Controlled

Blood sugar stays within target range using healthy eating and physical activity alone.

Treatment: Medical Nutrition Therapy · Daily Exercise · Glucose Monitoring

A2

A2GDM — Medication-Controlled

Blood sugar requires insulin or metformin to stay consistently within the safe range.

Treatment: All Lifestyle Changes + Medication + Additional Fetal Monitoring

Most women start with A1GDM. About 1 in 3 will eventually need medication (A2GDM). This classification also guides decisions about delivery timing.

Why Blood Sugar Control Matters

High blood sugar crosses the placenta and affects your baby's growth

Glucose Transfer

When your blood sugar is high, extra glucose crosses the placenta to your baby.

Baby's Insulin Response

Your baby's pancreas responds by making extra insulin, which acts like a growth hormone.

Macrosomia

This can cause your baby to grow larger than normal (estimated fetal weight > 4,000 g).

Controlling your blood sugar dramatically reduces all of these risks. Every healthy meal and every glucose check matters.

Potential Risks for Your Baby

Risk What It Means Prevention
Macrosomia Baby grows too large (>4,000 g) Blood sugar control
Shoulder Dystocia Shoulder gets stuck during delivery Blood sugar control + monitoring
Neonatal Hypoglycemia Low blood sugar right after birth Tight glucose control in labor
Breathing Difficulties Immature lung development Avoid early delivery when possible
Future Obesity / T2DM Long-term metabolic programming Breastfeeding + healthy family habits

The good news: controlling your blood sugar dramatically reduces all of these risks.

What Are the Risks for You?

GDM affects your health too — both now and in the future

During This Pregnancy

  • Preeclampsia (high blood pressure)
  • Cesarean delivery
  • Polyhydramnios (too much amniotic fluid)
50–70%

Risk of Type 2 Diabetes within 10 years

Higher lifetime cardiovascular risk

A GDM diagnosis is your body's early warning system. Acting now — with lifestyle changes — can protect your long-term health.

Your Blood Sugar Goals

Keeping your levels in this range helps protect your baby

Fasting
First thing in the morning
< 95
mg/dL
1 Hour After Meal
Start timing from first bite
< 140
mg/dL
2 Hours After Meal
Start timing from first bite
< 120
mg/dL

Your doctor will tell you whether to test 1 hour OR 2 hours after meals. You usually do not need to do both.

Targets per ACOG Practice Bulletin No. 190 · ADA Standards of Care

Checking Your Blood Sugar

Two ways to monitor your levels: Fingersticks and CGMs

Fingerstick — The Gold Standard

  • Most accurate — measures glucose directly from blood
  • Required for treatment decisions
  • Test fasting + 1 or 2 hours after each meal

CGM — Continuous Monitor

  • Measures fluid between cells, not blood directly
  • Readings can be 15–20 minutes behind actual blood sugar
  • Great for seeing trends and food responses

If your CGM reading does not match how you feel, or shows a very low/high number, always double-check with a fingerstick before treating.

Medical Nutrition Therapy

Food is your first medicine

Eat Consistently

Eat every 2–3 hours. Aim for 3 meals and 2–3 snacks daily to prevent sugar spikes and drops.

Pair Your Carbs

Never eat a "naked" carb. Always pair carbohydrates with protein or healthy fats to slow digestion.

Choose Quality

Choose complex carbohydrates (whole grains, veggies) over simple sugars (juice, sweets).

You do not need to eliminate carbohydrates. The goal is to choose the right type and amount to keep blood sugar stable.

Smart Food Choices

Focus on quality carbohydrates that digest slowly to keep blood sugar stable

✓ Choose More Often

  • Whole grains — brown rice, quinoa, oats, whole wheat
  • Non-starchy vegetables — spinach, broccoli, peppers
  • Legumes & beans — lentils, chickpeas, black beans
  • Whole fruits — berries, apples with skin, citrus
  • Healthy proteins & fats — nuts, avocado, eggs, lean meats

✗ Limit or Avoid

  • Refined grains — white bread, white rice, regular pasta
  • Sugary drinks — soda, fruit juice, sweet tea
  • Processed snacks — chips, crackers, granola bars
  • Sweets & desserts — cakes, cookies, ice cream
  • Sweetened breakfasts — sugary cereals, flavored yogurt

Exercise Is Medicine

Physical activity is one of the most powerful tools to lower blood sugar

The 10–15 Minute Walk

A short walk after each meal helps your muscles use up glucose naturally, lowering your numbers without medication.

Weekly Goal

Aim for 150 minutes of moderate activity per week — that's just 30 minutes a day, 5 days a week.

Safe Activities During Pregnancy

  • Walking
  • Swimming or water aerobics
  • Stationary cycling
  • Prenatal yoga
  • Light resistance training

Always check with your provider before starting a new exercise routine.

When Medication Is Needed

If diet and exercise are not enough, medication is safe and effective

Insulin

The preferred medication for GDM. Does not cross the placenta. Highly effective at controlling blood sugar.

Given as injections. Your diabetes educator will teach you how.

Metformin

An oral pill that reduces insulin resistance. Safe for use in pregnancy and well-studied.

Does cross the placenta in small amounts; long-term data are reassuring.

Needing medication does not mean you failed. It means your body needs extra help — and that help is available and safe.

Monitoring Your Baby

Close surveillance helps us catch and treat problems early

18–20 Weeks — Anatomy Ultrasound

Detailed survey of baby's organs, heart, and structure.

28–32 Weeks — Fetal Echocardiogram

Detailed look at baby's heart — GDM increases risk of cardiac defects.

32–36 Weeks — Growth Ultrasounds

Serial scans every 4 weeks to track baby's size and amniotic fluid.

32–36 Weeks — Nonstress Tests (NST)

Weekly or twice-weekly fetal heart rate monitoring for A2GDM patients.

A1GDM patients may need less monitoring. Your team will tailor the plan to your specific situation.

What Is a Nonstress Test (NST)?

  • You relax while sensors monitor baby's heart rate for 20–40 minutes
  • A "reactive" NST means baby's heart rate accelerates normally — reassuring
  • A "nonreactive" result does not automatically mean something is wrong
  • If NST is nonreactive → a biophysical profile (BPP) ultrasound is performed

What Is a BPP?

A biophysical profile uses ultrasound to assess baby's movements, breathing, muscle tone, and amniotic fluid — a comprehensive check.

These tests are reassurance tools. They help your team confirm your baby is doing well.

When Will I Deliver?

ACOG recommendations for delivery timing with GDM

GDM Type Blood Sugar Control Recommended Delivery
A1GDM Well-controlled on diet alone 39 weeks 0 days – 40 weeks 6 days
A2GDM Well-controlled on medication 39 weeks 0 days
A2GDM Poorly controlled 37–39 weeks (individualized)
Any GDM Macrosomia ≥ 4,500 g Cesarean delivery discussed

Your delivery plan is individualized. Your care team will discuss the safest timing for you and your baby.

ACOG Practice Bulletin No. 190 · SMFM Consult Series #58

What to Expect During Labor

Blood Sugar Monitoring

Your blood sugar will be checked every 1–2 hours during labor. The goal is to keep levels between 70–110 mg/dL.

IV Insulin (If Needed)

If blood sugar rises during labor, IV insulin may be given to protect your baby from neonatal hypoglycemia.

After Your Baby Is Born

  • Baby's blood sugar checked within the first hour
  • Early feeding (breastfeeding or formula) helps stabilize baby's glucose
  • Most babies do well and do not need special treatment
  • Your blood sugar typically normalizes within days of delivery

Your Postpartum Glucose Test

This is one of the most important follow-up steps after delivery

The Timing

Schedule your test between 4 and 12 weeks after your delivery.

The Test

The 75g 2-Hour Oral Glucose Tolerance Test — fasting + 2-hour blood draw.

Why Not A1C?

The A1C test is not recommended this soon after delivery. Blood loss and rapid cell turnover make it inaccurate.

Result Next Step
Normal Re-screen every 1–3 years
Prediabetes Lifestyle changes + consider Metformin
Diabetes Referral to Endocrinology

Reducing Your Long-Term Risk

Your action plan for a healthy future

Did You Know?

Women with GDM have a 7-fold increased risk of developing Type 2 Diabetes later in life.

Healthy Weight

Losing just 5–7% of your body weight can significantly lower your risk of diabetes.

  • Nutrition: Continue choosing complex carbs, lean proteins, and vegetables as a permanent lifestyle change
  • Activity: Aim for 150 minutes of moderate activity per week
  • Screening: Test for diabetes every 1–3 years — early detection is your best protection

Your Baby's Long-Term Health

Understanding how your pregnancy affects your child's future metabolism

Metabolic Programming

High blood sugar in the womb can "program" your baby's metabolism to store fat more easily.

Babies born to moms with uncontrolled GDM have a higher risk of childhood obesity and Type 2 Diabetes.

Breaking the Cycle

By keeping your blood sugar in range now, you are actively lowering these risks for your child.

After birth: breastfeeding, a healthy family diet, and keeping your child active are powerful ways to continue this protection.

"You are not just managing a condition — you are changing your family's health history."

Your Care Team

You are not alone — a team of experts is here to support you and your baby

  • OB/GYN Provider: Manages your overall pregnancy care, monitors blood pressure, and delivers your baby
  • Maternal-Fetal Medicine Specialist: Performs detailed ultrasounds, interprets fetal monitoring, and manages complex blood sugar issues
  • Registered Dietitian: Helps you create a personalized meal plan that fits your lifestyle while keeping blood sugar stable
  • Diabetes Educator: Teaches you how to use your glucose meter, interpret your numbers, and administer insulin if needed

We communicate regularly to ensure you and your baby receive the best coordinated care. You are the most important member of the team.

Questions to Ask Your Doctor

Be an active partner in your care — bring this list to your next visit

Reporting Numbers

How often and by what method should I send you my blood sugar logs?

Specific Targets

What are my specific goals for fasting and post-meal numbers? Should I test 1 or 2 hours after eating?

When to Call

At what blood sugar level should I call the office immediately?

Baby Monitoring

Will I need extra growth ultrasounds or nonstress tests? When do those start?

Delivery Plan

How does my diagnosis affect my delivery timing? Will I need to be induced?

Postpartum

When should I schedule my 2-hour glucose test after the baby is born?

Five Things to Remember

Key takeaways for a healthy pregnancy

01

It's Not Your Fault

GDM is caused by placental hormones blocking your insulin — not by something you did wrong.

02

Food Is Medicine

Complex carbs paired with protein and healthy fats is the most powerful way to control blood sugar.

03

Movement Matters

A 10–15 minute walk after meals helps your muscles use up glucose naturally.

04

Medication Is Safe

If diet isn't enough, insulin or metformin are safe tools to protect your baby.

05 — Follow Up Postpartum: Don't forget your 2-hour glucose test 4–12 weeks after delivery to ensure your diabetes has resolved.

❤️

You've Got This

Gestational diabetes is a challenge, but it is temporary. Every healthy meal, every walk, and every fingerstick is an act of love for your baby.

Questions? Write them down and bring them to your next appointment.

Based on ACOG Practice Bulletin No. 190 (Gestational Diabetes Mellitus) · SMFM Consult Series #58 · ADA Standards of Care · Atlanta Perinatal Associates