Glucose Tolerance Test While Pregnant

This test is done to help find out if you have diabetes while you are pregnant (gestational diabetes). It takes about 3 hours. You will have some waiting time between the times your blood is drawn.


  • Do not eat or drink anything but water after dinner the night before the test.

  • Arrive 10 minutes before your appointment to fill out any paperwork.


  • Your first blood sample will be taken.

  • You will be given a small bottle of sweet liquid to drink.

  • If you feel sick to your stomach (nauseous) or throw up (vomit), tell the lab technician.

  • Do not eat or drink anything but water.

  • Do not chew gum.

  • During the test, you should stay close to the lab so your other blood samples can be taken on time. This is important. If the blood samples are not taken on time, the test will need to be done again on another day.

  • When it is time, let the lab technician know that your blood sample needs to be taken.

  • Your second blood sample will be taken 1 hour after you drink the liquid.

  • After another hour, your third blood sample will be taken.

  • After one more hour, your last blood sample will be taken.

The timing of blood sampling may vary in different labs. The lab will let you know when the blood needs to be drawn.


  • You can eat and drink as usual.

  • Ask when your test results will be ready. Make sure you get your test results.