Gestational Diabetes Screening 2026: What to Expect

Last updated: January 2026

Gestational diabetes screening is a routine part of prenatal care. Understanding what to expect can help reduce anxiety and ensure accurate results. This guide covers everything you need to know about GD screening in 2026.

When You'll Be Tested

Standard Screening (24-28 Weeks)

All pregnant women are screened for gestational diabetes between 24-28 weeks of pregnancy. This is when the placenta produces enough hormones that insulin resistance becomes detectable.

Early Screening (First Trimester)

You may be tested earlier if you have risk factors:

• BMI of 25 or higher (or 23+ for Asian Americans)
• Previous gestational diabetes
• Family history of type 2 diabetes
• Polycystic ovary syndrome (PCOS)
• Previous baby weighing 9 pounds or more
• High blood pressure or heart disease
• African American, Hispanic, Native American, Asian, or Pacific Islander heritage
• A1C of 5.7% or higher at first prenatal visit

Types of Screening Tests

Two-Step Approach (Most Common in US)

Step 1: 1-Hour Glucose Challenge Test (50g)

• No fasting required (usually)
• Drink 50g glucose solution
• Blood drawn after 1 hour
• If result is 130-140 mg/dL or higher, proceed to Step 2

Step 2: 3-Hour Glucose Tolerance Test (100g)

• Fasting required (8-14 hours)
• Fasting blood draw first
• Drink 100g glucose solution
• Blood drawn at 1, 2, and 3 hours
• GD diagnosed if 2+ values exceed thresholds

One-Step Approach (75g OGTT)

• Fasting required (8-14 hours)
• Fasting blood draw first
• Drink 75g glucose solution
• Blood drawn at 1 and 2 hours
• GD diagnosed if ANY value exceeds threshold

Diagnostic Thresholds

3-Hour Test (100g) - Two-Step

Timing	Threshold (mg/dL)
Fasting	95 or higher
1 hour	180 or higher
2 hour	155 or higher
3 hour	140 or higher

Two or more values above threshold = GD diagnosis

2-Hour Test (75g) - One-Step

Timing	Threshold (mg/dL)
Fasting	92 or higher
1 hour	180 or higher
2 hour	153 or higher

Any one value above threshold = GD diagnosis

How to Prepare

For the 1-Hour Screening

• Usually no fasting needed (confirm with your provider)
• Eat normally in the days before
• Avoid excessive sugar the day before
• Plan 2+ hours at the lab/office
• Bring something to do while you wait

For the 3-Hour Diagnostic Test

• Fast for 8-14 hours before (water is okay)
• Eat normally for 3 days before (don't restrict carbs)
• Schedule first thing in the morning
• Plan 4+ hours at the lab/office
• Bring a book, snacks for after, and a ride home
• Wear comfortable clothes with easy arm access

What to Expect During the Test

1. Arrival: Check in and get settled
2. Fasting draw: Initial blood sample (if fasting test)
3. Drink the glucose: Usually orange or fruit punch flavored
4. Wait: Stay seated and calm; don't eat or drink
5. Blood draws: At 1, 2, and/or 3-hour marks
6. After: Eat a snack and go about your day

Tips for the Glucose Drink

• Drink it cold (ask the lab to refrigerate it)
• Drink it quickly (within 5 minutes)
• Some people find a straw helps
• Don't gulp - steady sips work best

Understanding Your Results

If You Pass

• No gestational diabetes at this time
• Continue routine prenatal care
• Maintain healthy eating habits

If You Need Further Testing

• Failing the 1-hour doesn't mean you have GD
• Many women pass the 3-hour after failing the 1-hour
• The 1-hour is designed to be sensitive to catch all possible cases

If You're Diagnosed with GD

• You'll meet with your healthcare team to create a plan
• Diet modification is the first-line treatment
• You'll learn to monitor your blood sugar
• Most women manage GD successfully with lifestyle changes

If diagnosed, see our 2026 GD diet guide and blood sugar targets to get started.

Common Concerns

Can I Fail on Purpose?

Some women wonder if eating low-carb before the test will help them pass. This is not recommended - it can lead to inaccurate results and miss a real diagnosis. Eat normally in the days before your test.

What If I Feel Sick?

Nausea is common during the test. Stay seated, take slow breaths, and notify the staff. Vomiting may require rescheduling the test.

Can I Do an Alternative Test?

Discuss options with your provider. Home monitoring or alternative foods may be offered in some cases, but the standard glucose drink remains the most accurate method.

Related Resources

• 2026 ADA Guidelines
• Blood Sugar Targets
• GD Diet Plan
• 7-Day Meal Plan

This guide is for informational purposes only. Your healthcare provider will give you specific instructions for your screening.