The test, taken as part of the screening for gestational diabetes, will measure the levels of glucose (sugar) in your blood usually between the 24th and 28th week of pregnancy. However, if you’ve had gestational diabetes before, or seem to be at a higher risk genetically, your doctor may choose to run the test as early as the 13th week.
Don’t sweat it: The test is simple and (relatively) painless. When you take the test, your doctor will ask you to quickly drink a sample of Glucola (basically a sweetened drink) that contains 50 grams of glucose. Make sure you clear your schedule (and a path to the bathroom) the day of your appointment — you’ll need to wait a full hour while your body absorbs the glucose before your doctor can take a sample of your blood. The results will show if your body has been responding to glucose positively or negatively.
If your results are positive, you'll need to have another screening — the 100-gram oral glucose tolerance test. During this one you’ll be tested four times over a three-hour time span. (Make sure to pack some good reading material!) If two out of the four test results show abnormality, you will be clinically diagnosed with gestational diabetes and will need to discuss a health plan for the remainder of your pregnancy with your doctor.
Source : American College of Obstetrics and Gynecologists. Your Pregnancy and Birth. 4th ed. Washington, DC: ACOG; 2005
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