Does this test have other names?

Glucose, postprandial; glucose, 2-hour postprandial; 2-hour PPG; 2-hour postprandial blood sugar

What is this test?

The 2-hour postprandial glucose test is a blood test to check for diabetes. If you have diabetes, your body doesn't make enough insulin to keep your blood sugar in check. This means your blood sugar levels are too high, and over time, this can lead to serious health problems, including heart, nerve, kidney, and eye damage.

Postprandial means after a meal. This test is done to see how your body responds to sugar and starch after you eat a meal. As you digest the food in your stomach, blood glucose, or blood sugar, levels rise sharply. In response, your pancreas releases insulin to help move these sugars from the blood into the cells of muscles and other tissues to be used for fuel. Within 2 hours of eating, your insulin and blood glucose levels should return to normal. If your blood glucose levels remain high, you may have diabetes.

Why do I need this test?

You may need this test if your doctor wants to see if you have diabetes or another insulin-related disorder, especially if you have symptoms such as:

• Frequent urination.

• Unusual thirst.

• Blurred vision.

• Tiredness.

• Repeated infections.

• Sores that heal slowly.

If you're pregnant, you may have this test to screen for gestational diabetes. This is diabetes that can develop during pregnancy. Treating gestational diabetes reduces the risk for health problems for you and your baby.

What other tests might I have with this test?

Your doctor may order other tests to confirm or evaluate whether you have diabetes. These may include:

• Fasting blood glucose test. This measures the amount of sugar in your blood when you have not eaten for at least 8 hours.

• Hemoglobin A1C (glycosylated hemoglobin) test. This measures your average blood sugar level over the last 2 to 3 months.

• Glucose tolerance test. This measures your body's ability to use sugar after drinking a standard amount in a sugary drink. 

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Ask your doctor what your test results mean for you.

Test results vary by age and are usually measured in milligrams per deciliter (mg/dL). Normal results for the 2-hour postprandial test based on age are:

• For those who don't have diabetes: less than 140 mg/dL

• For those who have diabetes: less than 180 mg/dL 

If your blood glucose level is still high 2 hours after you've eaten, or if it is high 1 hour after a gestational diabetes glucose tolerance test, it could mean you have diabetes.

How is this test done?

The test is done by taking a blood sample before and 2 hours after a meal or special sugar drink. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

Your test results might be affected if you:

• Smoke during the test period.

• Are under extreme stress.

• Eat a snack or candy after your meal and before you're tested.

• Are unable to eat the entire meal.

• Exercise during the testing period.

How do I get ready for this test?

Your doctor will instruct you how to prepare for this test. You will be told what and when to eat. You may be asked to drink a glucose (sugary sweet) liquid with 75 grams of sugar instead of eating food. Plan on resting during the 2-hour waiting period before your blood is drawn again.

Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any drugs you may use.