My doctor says I have to take a three-hour glucose test for gestational diabetes. I've known a lot of women who've had it, and I'm scared to take the test because I've seen what they go through when it's positive...poking themselves all the time and eating a special diet. I've also heard that the test is often wrong, and that scares me even more! What can I do??
Yes, it's true -- there are a lot of false positives in gestational diabetes testing. There are also a variety of different tests, and the numbers that mean you "pass" can be different from test to test. So you need to know what standard the test results are based on in order to properly interpret the results.
The two-hour postprandial "screen" will have fewer false positives than the three-hour glucose tolerance test (GTT
) which is most commonly used in medical practices today. capillary whole blood concentration of glucose. This test consists of eating a high-carbohydrate breakfast, then having your blood drawn two hours later.
According to The Brewer Pregnancy Hotline: "In pregnancy, the values considered the upper limit of "normal" by the Diabetes Data Group for fasting glucose level and the GTT are far lower than this: a fasting level of 105 milligrams per milliliters, at one hour-190; two hours-165; three hours-145. These levels tend to be too low for women following the Brewer Pregnancy Diet and the reason is the following: On the Brewer Pregnancy Diet, expectant mothers are able to meet their babies' glucose needs without lowering their own. It is clear that most pregnant women exhibit lower plasma glucose levels than the rest of the adult population because they are not being advised to eat as well as they need to. If you are following the Brewer Pregnancy Diet and your doctor insists on a GTT, he or she should use the new diagnostic criteria established for non-pregnant individuals to avoid making an incorrect diagnosis of diabetes in your case."
The following can affect your GTT, causing a false postive result:
- stress or anxiety (yes, even over the procedure itself!)
- having a cold or flu when you take the test
- lack of physical exercise (e.g., sitting in the waiting room waiting to have your blood drawn)
- inadequate diet (see the rest of this site for information on conquering that!)
If you are going to take the GTT you'll want to load up on carbohydrates (starchy foods such as breads, potatoes, rice, pasta, sugars) for three days prior to the test. These help your liver store up glycogen in preparation for the all-night fast imposed by the GTT protocol. This glycogen reserve can then be called upon to stabilize your blood sugar during the period when you are without food. According to The Brewer Pregnancy Hotline: "Without carbohydrate loading you exhaust your liver's storage of glycogen overnight and possibly test out with a diabetic curve when, in fact, you are not diabetic at all -- just temporarily glycogen-depleted."