You can refuse any test. However, I think you should do so only after evaluating all relevant information for yourself.
One reason why gestational diabetes screening has become universal is that GD can be completely silent- you can feel fine even with abnormally high blood sugar. The other reason that GD screening has become so common is that it can increase the baby's risk for complications that can, at times, be severe. These complications include neonatal hypoglycemia due to overproduction of insulin by the baby and higher incidence of macrosomia or extreme large size which can make birth more difficult. Some new research has also found that babies born to GD moms are more likely to become diabetic themselves.
The 1-hour test for GD is sensitive
but not diagnostic
. The 1-hour test is a screening test
, and screening tests are designed
to catch all possible cases
of a problem (a.k.a. sensitive) but not to identify actual cases (a.k.a. diagnostic). The high rate of false positives on a screening test is a natural outcome of the design of the test: the goal is to catch everyone with GD, even though that means that some women who do not have GD will "fail" the 1-hour test and therefore be subjected to the 3-hour test. Most women pass the 1-hour test. Of those who do not, 70% (if I remember correctly) will go on to "pass" the more accurate 3-hour test.
You do not have to fear being labeled "gestationally diabetic" merely by failing the 1-hour screening test. If you fail the 3-hour diagnostic test, however, you will probably get the GD label. Women who fail the 3-hour test who are mistakenly labeled will go on to do self-testing which will reveal their non-GD status.
Who should be tested for GD? IMHO, anyone who has significant risk factors for impaired glucose tolerance during pregnancy should consider taking the test, or at least self-monitoring on a regular basis. This includes:
- Women with a family history of diabetes
- Women with PCOS (Polycystic Ovarian Syndrome)
- Women who are significantly overweight
- Women who are older
- Women who are spilling sugar in their urine
If you do decide to take the test, and do discover that you have GD, ask yourself, and your OB this question: how will having GD change my treatment? If your OB says "Well, we'll want you to monitor your diet, and get more exercise, and do some self-testing with a home blood glucose meter, but that's about it" then you have nothing to fear. If you hear "Well, I don't let my GD patients go past their due dates and I do a lot of inductions to prevent babies from growing too large," then it's time to run.
Preferably to a midwife!