How is gestational diabetes diagnosed?

All pregnant women, whether they are in a high risk group or not, are typically screened for gestational diabetes.

This usually occurs between 26 and 28 weeks of pregnancy, when the hormones that cause gestational diabetes are at high levels. You do not need to do anything for this screening test.

Any woman might develop gestational diabetes during pregnancy.

Screening for gestational diabetes

The typical steps for the screening test at your health care provider's office are:

  • You drink a 50-gram glucose beverage.
  • You sit quietly for one hour.
  • Your blood glucose level is measured. A result more than 140 is considered a positive glucose screen.

If you have a positive result, you may be given a three-hour glucose tolerance test on another day to confirm if you have diabetes.

Diagnosing gestational diabetes

The typical steps to confirm gestational diabetes using the glucose tolerance test are:

  1. You fast the night before the test. On the days before the test, you should eat normally.
  2. Your fasting blood glucose is measured before the test begins.
  3. You drink a 100-gram glucose beverage at your health care provider's office or lab.
  4. You sit quietly for three hours.
  5. Your blood glucose is measured at the one-, two-, and three-hour time spans during the three-hour period.
  6. Two or more elevated test results means you have gestational diabetes.

Your health care provider will review your test results and tell you what happens next. Information covered may include:

  • a special meal plan
  • blood glucose monitoring
  • urine testing for ketones
  • exercise guidelines
  • medicine therapy

Your health care provider's clinic may have a diabetes dietitian or educator help you, or you may be referred to a diabetes center at your hospital.

Source: Allina Health's Patient Education Department, Gestational Diabetes: When You Have Diabetes During Pregnancy, third edition, ISBN 1-931876-21-6
Reviewed By: Reviewed by Allina Health's Patient Education Department experts
First Published: 11/27/2006
Last Reviewed: 01/20/2014