Between your 26th and 28th week of pregnancy, you will be screened for gestational diabetes.
This test is called a one-hour glucose tolerance test. In some instances, depending on your history, you may be screened for diabetes earlier in pregnancy. This test consists of drinking a concentrated sugar beverage and having a blood sample drawn one hour after ingestion of the beverage. You are not to eat or drink anything for that hour, but it is not necessary to fast before taking the test.
A blood glucose value under the 130-140 mg/dl range is considered normal, and no further testing is indicated. If the blood glucose value is above the 130-140 mg/dl range, however, then you will be scheduled for a three-hour glucose tolerance test. This test consists of going to the lab in the morning after fasting from midnight the night before. You will then have a blood sample drawn each hour after this for three hours. You will not be allowed to eat or drink during this test. If two or more of the 3-hour glucose blood values come back elevated, you will be considered to have gestational diabetes. Your physician will plan your care according to the actual result of your test.