Friday, February, 10, 2012

Glucose tolerance test

Table of Contents

Alternative Names

Oral glucose tolerance test


Normal Values

Normal blood values for a 75-gram oral glucose tolerance test used to check for type 2 diabetes:

  • Fasting: 60 -100 mg/dL
  • 1 hour: less than 200 mg/dL
  • 2 hours: less than 140 mg/dL. Between 140 - 200 mg/dL is considered impaired glucose tolerance (sometimes called "prediabetes"). This group is at increased risk for developing diabetes. Greater than 200 mg/dL is a sign of diabetes mellitus.

Normal blood values for a 50-gram oral glucose tolerance test used to screen for gestational diabetes:

  • 1 hour: equal to or less than 140 mg/dL

Normal blood values for a 100-gram oral glucose tolerance test used to screen for gestational diabetes:

  • Fasting: less than 95 mg/dL
  • 1 hour: less than 180 mg/dL
  • 2 hour: less than 155 mg/dL
  • 3 hour: less than 140 mg/dL

Note: mg/dL = milligrams per deciliter

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.


What abnormal results mean

Greater than normal levels of glucose may mean you have diabetes or gestational diabetes.

However, high glucose levels may be related to another medical problem (for example, Cushing syndrome).


Review Date: 05/23/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)