1 hour and 2 hour Glucose Tolerance Test During Pregnancy

2 hour Glucose Tolerance Test

The oral glucose tolerance test (OGTT) is also known as the glucose tolerance test. It’s a 2-hour test to assess your body’s reaction to sugar (glucose).

Type 2 diabetes can be detected using the glucose tolerance test. A modified version of the glucose tolerance test is more commonly used to diagnose gestational diabetes, which is a type of diabetes that develops during pregnancy.

The test is made available to:

  • Selected expectant mothers at 26 weeks;
  • All expectant mothers with a history of diabetes at 16 weeks. At 26 weeks, the test will be repeated if the results at 16 weeks are normal.
  • Any pregnant woman who exhibits diabetic symptoms, such as extra fluid surrounding the fetus or a large baby.
You may also like to read:

Why it’s done and the risks involved

The 2-hour glucose tolerance test finds issues with how your body processes glucose after a meal, frequently before your fasting blood glucose level does.

Getting a blood sample carries just a little amount of danger. You can have bleeding or bruising after having your blood drawn.

Additionally, you can experience fainting or a dizzy feeling. After your procedure, infection is a possibility in specific circumstances.

Getting ready for the GTT

  • Maintain your regular diet for the week leading up to the test.
  • The night before the exam, you are only permitted to consume water after 9.30 p.m. No other food or beverage is permitted.
  • Only clear, flavorless water may be consumed before the test, you must refrain from eating or chewing gum.
You may also like to read:

Procedure to Conduct 2-hour Oral Glucose Tolerance Test

  • The examination will last roughly 2.5 hours.
  • A fasting blood sample is collected from a vein in your arm when you arrive.
  • You’ll next receive a drink with a measured amount of glucose.
  • A second blood sample will be taken from your arm two hours later.
  • You may only drink clear water up until the test is over; no other food or beverages (apart from water) are permitted.
  • It’s advised that you refrain from smoking throughout the test because it could skew the results.
  • Until the test is finished, you must remain at the hospital. You should remain still and avoid moving about or engaging in any physical activity. You are permitted to wait in your parked automobile outside the premises as long as social distance criteria are met.
  • You are permitted to wait in your parked automobile outside the premises as long as social distance criteria are met.
  • Following the test, you are free to eat and drink as usual.
  • This test has no dangers attached to it [Ref].
You may also like to read:

Results of 2-hour Glucose Tolerance Test:

Regarding the three-hour exam:

  • A fasting blood glucose level of less than 95 mg/dL (5.3 mmol/L) is considered normal.
  • A normal blood glucose level is less than 180 mg/dL (10 mmol/L) an hour after consuming the glucose solution.
  • A normal blood glucose level is less than 155 mg/dL (8.6 mmol/L) two hours after consuming the glucose solution.
  • A normal blood glucose level is less than 140 mg/dL (7.8 mmol/L) three hours after consuming the glucose solution [Ref].

If one of the results is higher than expected, you will most likely need to retest in four weeks. You will be diagnosed with gestational diabetes if two or more of the results are higher than normal.

You may also like to read:

One-hour Glucose Tolerance Test

The one-hour glucose tolerance test, often known as the glucose challenge test, gauges how your body reacts to sweets (glucose).

If you’re at average risk of gestational diabetes, you’ll likely be screened during your second trimester between 24 and 28 weeks of pregnancy. You can take the glucose challenge test without fasting beforehand.

Procedure to Conduct 1-hour GTT

  • The glucose challenge test is carried out in two stages.
  • When you arrive at your doctor’s office or the lab, you’ll be given a syrupy glucose solution containing 1.8 ounces (50 grams) of sugar.
  • You must wait for your blood sugar level to be measured in the lab or at the office of your healthcare practitioner. Other than water, you are not allowed to eat or drink anything during this time.
  • A blood sample will be drawn an hour later from a vein in your arm. You’ll have your blood sugar level checked using this sample of blood.
You may also like to read:

Results of 1-hour GTT:

The glucose challenge test results are reported in millimoles per liter (mmol/L) or milligrams per deciliter (mg/dL).

  • A normal blood sugar level is less than 140 mg/dL (7.8 mmol/L).
  • When the blood sugar level ranges from 140 mg/dL (7.8 mmol/L) to less than 190 mg/dL (10.6 mmol/L), a three-hour glucose tolerance test is required to determine whether gestational diabetes is present.
  • Gestational diabetes is identified by a blood sugar level of 190 (10.6 mmol/L) or above. Perhaps no additional testing is required.
  • When screening for gestational diabetes, some clinics or labs utilize a lower threshold of 130 mg/dL (7.2 mmol/L).

If gestational diabetes is identified in you, you can avoid difficulties by closely monitoring your blood glucose level for the remainder of your pregnancy.

A two-hour glucose tolerance test should be administered to women with gestational diabetes 4 to 12 weeks after delivery, according to the American College of Obstetricians and Gynecologists [Ref].

You may also like to read:

What do you think?

Written by Dr. Ahmed

I am Dr. Ahmed (MBBS; FCPS Medicine), an Internist and a practicing physician. I am in the medical field for over fifteen years working in one of the busiest hospitals and writing medical posts for over 5 years.

I love my family, my profession, my blog, nature, hiking, and simple life. Read more about me, my family, and my qualifications

Here is a link to My Facebook Page. You can also contact me by email at or at My Twitter Account
You can also contact me via WhatsApp 🙏

type 1 diabetes and pcos

Type 1 Diabetes and PCOS

gestational diabetes delivery

Gestational Diabetes: Risks and Average Time of Delivery