What to Eat Before a Glucose Test: Everything You Need to Know
Knowing what to eat before a glucose test is crucial for accurate blood glucose level results. This guide provides information on the best foods for stable blood sugar, what to avoid, and how to prepare for reliable readings.
Key Takeaways
Eat balanced meals with complex carbohydrates and lean protein in the days leading up to a glucose screening test. This helps stabilize blood sugar and provides a consistent baseline for the test. Avoid making drastic changes to your diet right before the test.
Fast for 8–14 hours before an oral glucose tolerance test (OGTT), consuming only water during this period. This ensures that your blood sugar levels are not influenced by recent food intake.
After the test, monitor your blood sugar levels and consume a diet rich in whole grains, lean proteins, and non-starchy vegetables to support overall glucose management and maintain stable blood sugar.
Types of Glucose Tests: What You Need to Know
There are several types of glucose tests used to assess how your body processes sugar. Each test serves a specific purpose and follows different procedures:
1. Glucose Challenge Test (GCT) – 1-Hour Test
✔ Used as a screening test for gestational diabetes.
✔ No fasting required—drink a 50g glucose solution, and blood is drawn after 1 hour glucose test.
✔ If results are elevated, a 3-hour Oral Glucose Tolerance Test (OGTT) is needed for confirmation.
2. Oral Glucose Tolerance Test (OGTT) – 2-Hour or 3-Hour Test
✔ Diagnoses gestational diabetes or prediabetes. The Oral Glucose Tolerance Test is specifically used to diagnose gestational diabetes by measuring how your body processes glucose.
✔ Requires fasting for 8–14 hours beforehand.
✔ You drink a 75g (2-hour test) or 100g (3-hour test) glucose solution, with blood drawn at intervals to track sugar levels.
✔ Higher-than-normal readings at multiple time points indicate gestational diabetes or impaired glucose tolerance.
3. Fasting Blood Glucose Test
✔ A simple blood test taken after fasting overnight (at least 8 hours).
✔ Used to screen for diabetes or prediabetes.
✔ A fasting glucose level ≥126 mg/dL usually indicates diabetes.
4. Hemoglobin A1C Test (HbA1c)
✔ Measures average blood sugar levels over the past 2–3 months.
✔ Does not require fasting.
✔ Commonly used for diabetes diagnosis and long-term blood sugar management.
✔ An HbA1c ≥6.5% suggests diabetes.
Preparing for Your Glucose Screening Test
A glucose screening test, commonly done during pregnancy, measures how your body processes sugar. Eating balanced meals with complex carbs and protein before the test helps stabilize blood sugar levels.
Should you change your diet before the test? Not drastically. Experts recommend eating normally to ensure reliable results. However, avoiding foods that cause rapid blood sugar spikes is key. According to the American Diabetes Association, maintaining your usual eating habits before a glucose screening test is important for accurate results. They advise against making significant changes to your diet in the days leading up to the test, as this could affect how your body responds to glucose. ACOG also says there is no need to alter the usual diet or activity before the test.
Balanced Meals to Eat Before a Glucose Test
Balanced meals help regulate blood sugar levels. Complex carbohydrates provide a steady glucose source, while protein and healthy fats help prevent spikes and promote satiety.
Examples of blood sugar-friendly meals:
Breakfast: Whole wheat toast + scrambled eggs
Lunch: Grilled chicken + quinoa + leafy greens
Dinner: Salmon + roasted vegetables + brown rice
Snacks: Greek yogurt + nuts | Cheese + whole-grain crackers
👉 Consistency is key: Eating at regular intervals throughout the day helps maintain stable blood sugar levels.
Foods to Avoid Before a Glucose Test
Certain foods can spike blood sugar, leading to inaccurate test results:
🚫 Refined carbohydrates & processed foods: White bread, pastries, sugary cereals
🚫 Sugary drinks: Soda, fruit juice, energy drinks
🚫 High-sugar snacks: Candy, cookies, flavored yogurt
Alternative: Opt for whole, fiber-rich foods like vegetables, nuts, and protein sources instead.
Getting Ready for the Oral Glucose Tolerance Test (OGTT)
For oral glucose tolerance tests (OGTT)—often used to diagnose gestational diabetes mellitus—you will need to fast before drinking a glucose solution.
Fasting Guidelines for OGTT
✔ Fast for 8–14 hours before the test (only water is allowed).
✔ Avoid any high-sugar foods the night before to prevent misleading results.
Tip: Your last meal before fasting should be balanced and similar to your usual diet—avoid sugary pancakes or juice.
What to Eat the Night Before a Glucose Test
Your evening meal before a pregnancy glucose test should include:
✔ Complex carbohydrates (whole grains, legumes)
✔ Lean protein (chicken, fish, tofu)
✔ Healthy fats (avocado, nuts)
Avoid excessive sugar, but don’t drastically change your diet. Your body should react to the test naturally.
How Diet Affects Blood Sugar Levels
Maintaining stable blood sugar is essential for gestational diabetes prevention and general health. The right macronutrient balance makes a difference. For guidelines on blood sugar levels, refer to the National Institute of Diabetes and Digestive and Kidney Diseases, which also provides information on kidney diseases. For guidelines on blood sugar levels specific to gestational diabetes, refer to the American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin on Gestational Diabetes Mellitus. They provide comprehensive recommendations for target blood glucose levels during pregnancy. Additionally, the International Diabetes Federation (IDF) offers global guidelines for managing gestational diabetes, including target blood glucose levels. Their recommendations can be found in the IDF Diabetes Atlas.
Best Carbohydrates for Blood Sugar Control
✔ Whole grains & fiber-rich foods (brown rice, quinoa, oats)
✔ Low-glycemic index carbs (sweet potatoes, legumes)
🚫 Avoid refined grains like white bread and pasta, which cause rapid sugar spikes.
The Role of Protein in Blood Sugar Regulation
Protein stabilizes glucose levels and supports fetal development during pregnancy.
Best protein sources: Eggs, lean meats, fish, dairy, tofu, legumes
Recommended intake: 6–8 oz per day for pregnant women
Post-Test Considerations: Monitoring Blood Sugar Levels
After the test, watch for symptoms like nausea or dizziness from the glucose solution. Monitoring your post-test blood sugar can help identify patterns for better management.
Healthy eating tips after the test:
✔ Prioritize fiber-rich foods (non-starchy vegetables, whole grains)
✔ Include lean proteins (chicken, fish, beans)
✔ Avoid high-sugar snacks & sweetened beverages
Regular physical activity also helps maintain stable glucose levels.
Understanding Your Glucose Test Results
Your doctor will analyze your blood glucose levels after the test.
Typical Glucose Tolerance Test (GTT) Results:
Fasting: ≤95 mg/dL
1-hour after glucose drink: ≤180 mg/dL
2-hour after glucose drink: ≤155 mg/dL
3-hour after glucose drink: ≤140 mg/dL
Two or more elevated results indicate gestational diabetes. A follow-up with your doctor is necessary.
How to Maintain Healthy Blood Sugar Levels
🔹 Eat balanced meals (protein + fiber + healthy carbs)
🔹 Avoid processed sugar and high-glycemic foods
🔹 Stay active—exercise helps regulate blood sugar
🔹 Monitor blood sugar levels if at risk for diabetes
Maintaining a healthy diet and lifestyle will help keep your glucose levels in check.
Final Thoughts
Preparing for a glucose test is simple with the right approach—eat a balanced diet, follow fasting guidelines, and understand how food impacts your blood sugar. By making informed choices, you can ensure accurate test results and better glucose management.
What If You’re Diagnosed with Gestational Diabetes?
If you end up diagnosed with gestational diabetes (GD), remember it’s not your fault. GD is caused by the hormonal changes during pregnancy that can interfere with your body’s ability to process insulin, leading to higher blood sugar levels. It’s a common condition affecting many pregnant women, and you're not alone in this journey.
With the right support, lifestyle changes, and healthy habits, gestational diabetes is manageable. It may seem overwhelming at first, but with your healthcare team’s guidance and determination, you can manage your blood sugar levels and ensure a healthy pregnancy for you and your baby.
For support and connection with other GD mamas, head to the HIgedi app. This is a great place to share meal ideas, snacks, and tips that make the journey a bit easier. Being part of a supportive community can make all the difference, so don't hesitate to reach out and connect with others who understand what you're going through.
Always consult your healthcare provider for personalized advice.
FAQ: Glucose Test
1. What should I eat before a glucose test?
Eat balanced meals with complex carbohydrates and protein while avoiding high-sugar and processed foods.
2. How long should I fast before a glucose test?
Fasting for 8–14 hours before the test ensures accurate results.
3. What happens during a glucose test?
You will drink a glucose solution, and your blood sugar will be measured over time to assess how your body processes sugar.
4. What if my glucose test results are high?
Consult your doctor for further testing and a possible management plan.
5. How can I keep my blood sugar stable after the test?
Eat balanced meals, avoid sweetened drinks, and stay active to support healthy glucose levels.
6. Can I drink water before a glucose test?
In most cases, you can drink plain water before a glucose test. Always confirm this with your healthcare provider.
7. How does exercise affect glucose test results?
Intense exercise can temporarily lower blood sugar levels. It's generally advised to avoid strenuous exercise 24-48 hours before the test.
8. What's the difference between a glucose screening test and an oral glucose tolerance test (OGTT)?
A screening test is typically shorter and involves one blood draw, while an OGTT is longer and involves multiple blood draws over several hours.
9. Can stress affect my glucose test results?
Yes, stress can elevate blood sugar levels. Try to relax before and during the test for the most accurate results.
10. What should I do if I accidentally eat or drink before a fasting glucose test?
Contact your healthcare provider immediately. They may need to reschedule the test to ensure accurate results.
11. Can medications affect glucose test results?
Yes, certain medications can influence blood sugar levels. Inform your healthcare provider about all medications you're taking before the test.
12. Is it safe to drive after a glucose test?
Some people may feel dizzy or nauseous after the test. It's advisable to have someone accompany you or be prepared to wait until you feel well enough to drive.
13. How long does it take to get glucose test results?
Results are often available within a few days, but this can vary. Ask your healthcare provider when you can expect to receive your results.