Quick Facts
- Sample: Blood (venous plasma)
- Fasting: No fasting required
- Turn-around: 1-2 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- No fasting required - convenient screening at any time of day
- Early detection of gestational diabetes prevents serious complications for mother and baby
- High accuracy with 79% sensitivity for detecting gestational diabetes
- Quick results available within 1-2 business days for immediate peace of mind
- Cost-effective alternative to traditional healthcare pathways
- Privacy maintained with secure, direct-to-consumer results delivery
Who Is This Test For?
- All pregnant women between 24-28 weeks of pregnancy for routine screening
- High-risk women with obesity, family diabetes history, or previous gestational diabetes
- Early pregnancy screening for women with PCOS or metabolic disorders
- Previous gestational diabetes patients requiring monitoring in subsequent pregnancies
- Symptomatic women experiencing excessive thirst, frequent urination, or fatigue
How It Works – Just 3 Steps
- Drink glucose solution containing 50 grams of glucose within 5 minutes
- Wait exactly one hour while remaining seated and avoiding exercise
- Blood draw measures your glucose level to screen for gestational diabetes
FAQ
When is the best time to get this test? The optimal timing is between 24-28 weeks of pregnancy for routine screening, though high-risk women may need earlier testing.
Do I need to prepare for this test? No fasting is required. Eat normally before the test but avoid eating during the one-hour waiting period.
What happens if my results are abnormal? Results above 135 mg/dL require a follow-up 3-hour glucose tolerance test to confirm gestational diabetes diagnosis.
How accurate is this screening test? The 50g glucose challenge test demonstrates 79% sensitivity and 74% specificity for detecting gestational diabetes.
Can I take medications before the test? Continue your regular medications unless specifically advised otherwise by your healthcare provider.
What are the risks if gestational diabetes goes undetected? Untreated gestational diabetes increases risks of preeclampsia, preterm delivery, and developing type 2 diabetes later in life.
More Details
What is the purpose of this test?
The 50-gram Glucose Challenge Test (GCT) screens for gestational diabetes mellitus (GDM) during pregnancy by measuring how your body processes glucose. This one-hour, non-fasting blood test is the gold standard for gestational diabetes screening, used to identify women at risk for developing high blood sugar that could harm both mother and baby (Mayo Clinic 2023).
Gestational diabetes affects up to 10% of pregnancies and can lead to serious complications including preeclampsia, preterm delivery, and increased risk of developing type 2 diabetes later in life. Early detection through this screening test enables timely intervention and comprehensive diabetes management to protect maternal and fetal health.
Who would benefit from this test?
All pregnant women should receive this screening between 24-28 weeks gestation as recommended by the U.S. Preventive Services Task Force (USPSTF 2021). Women with risk factors including obesity, family history of diabetes, previous gestational diabetes, or PCOS may benefit from earlier testing, potentially as early as the first prenatal visit.
This test is particularly valuable for health-conscious consumers using direct-access laboratory services, offering convenience, privacy, and cost-effectiveness while ensuring adherence to established clinical guidelines. Women who experienced gestational diabetes in previous pregnancies require careful monitoring with this test in subsequent pregnancies.
When should I order this test?
Optimal timing is 24-28 weeks of pregnancy for routine screening. High-risk women may need testing as early as the first prenatal visit (Women's Preventive Health 2024). The test can be performed at any time of day without dietary restrictions, making scheduling convenient around your daily routine.
For women with multiple risk factors or symptoms suggestive of gestational diabetes, earlier and more frequent testing may be recommended. Consult with your healthcare provider to determine the most appropriate timing based on your individual risk profile and pregnancy history.
How do I interpret the results?
Glucose Level: ≤135 mg/dL
- What it means: Normal screening result
- Typical action: Continue routine prenatal care
Glucose Level: 136–189 mg/dL
- What it means: Abnormal screening result
- Typical action: 3-hour glucose tolerance test needed
Glucose Level: ≥190 mg/dL
- What it means: Likely gestational diabetes
- Typical action: May diagnose without additional testing
Women with gestational diabetes face a 35-60% risk of developing type 2 diabetes within 10-20 years after pregnancy, emphasizing the importance of long-term follow-up.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting is required for this test, making it convenient for routine prenatal care. Eat normally before the test but avoid dieting for three days prior, as this may cause inaccurate results. Maintain normal carbohydrate intake of 150-200 grams daily for accurate metabolic assessment (BCOG Guidelines).
Continue taking regular medications unless specifically contraindicated by your healthcare provider. Schedule your appointment at a convenient time, as you'll need to remain at the laboratory for the one-hour waiting period. Avoid exercise during the waiting period to prevent falsely low results.
How often should I get tested?
- Normal pregnancy (routine screening): Once between 24–28 weeks
- High-risk factors present: Early pregnancy + 24–28 weeks
- Previous gestational diabetes: Each subsequent pregnancy
- Abnormal initial screening: Follow-up 3-hour test within 1–2 weeks
Why early detection matters
Gestational diabetes affects 6.9% of pregnancies in the United States, with significant health and economic implications (CDC 2024). Each case is associated with approximately $5,800 in additional medical expenditures, with total national economic impact reaching $1.56 billion annually.
Early detection through screening enables implementation of dietary counseling, glucose monitoring, and possible medication to prevent complications. Women with gestational diabetes can reduce their risk of adverse outcomes through proper management, and early intervention can reduce the risk of developing type 2 diabetes later in life by up to 32% through lifestyle modifications.
Related tests you may consider
Glucose Tolerance Test (GTT) Blood Test, 3-Hour, 4 Specimens - checks how your body handles sugar over three hours by taking four blood samples to help doctors find or manage diabetes, prediabetes, or gestational diabetes.
Hemoglobin A1c (HbA1c) - calculates the average blood glucose levels over 2-3 months, making it an ideal diagnostic tool for diabetes management.
Diabetes #2 Essential Blood and Urine Test Panel - Evaluates a Complete Metabolic Panel (CMP-14) with Glucose, Complete Blood Count (CBC)'s, Hemoglobin A1C plus Insulin, Urinalysis, Microalbumin/Creatinine Ratio Urine, and C-Peptide.
