There are two test commonly administered to screen for GD and one is fasting while the other is not. It does not matter which test is used, though most doctors in the US prefer the nonfasting for reasons of patient comfort.
The test is non-invasive and carries no known risks.
I have a healthy BMI of 19, and have never been overweight. My family is 100% organic, macrobiotic and vegan. I work out six times a week, and I cycle semi-professionally. At 22 weeks, I was given a routine GTT, and failed. Badly. Anything over 140 is a "fail," and my numbers? 460. I had no symptoms. I went in for the three hour test (because everyone, midwife included, was sure the first test was in error), and I failed that, too. I was referred to a doctor specializing in gestational diabetes, who coordinated care with my midwife. They quickly discovered I was in the early stages of a type of diabetes known as Latent Autoimmune Diabetes of Adults. The onset is so gradual, that many people only know they have LADA after going into DKA (a type of serious diabetic complication wherein the body shuts down due to high blood glucose). Obviously, during pregnancy, this can be all the more serious, and most infants would not survive the long term elevation in blood sugar, or would experience serious child-birth related complications. In short, that routine test saved my life. I would NEVER advise a woman, no matter her lifestyle or health habits, to forgo that test. My friend, actually, counseled me not to have it, saying it was just another way of turning pregnancy into a medical condition requiring management, and that I did not need it being so low risk for GD. Thank God I didn't listen!
Incidentally, I continued care with my midwife, and gave birth at an area birthing center with no internal monitoring, and no other interventions of any kind. It was a beautiful birth. I was able to walk around, lay in the jacuzzi tub, and then delivered naturally in a short, easy labor. My baby was perfectly healthy. Her sugars were a bit low after delivery but, after nursing immediately after birth, she was just fine. Getting diagnosed did not change my birth plan or care. In fact, if I had not gotten diagnosed, I would have certianly required a ton of monitoring and probably a c-section due to diabetes-related complications!
Edited by NatureMom2Two - 7/24/11 at 7:50am