Glucose Tolerance Test at 26 Weeks: Timing & Gestational Diabetes

Question
Hi,

When I was 26 pregnant weeks my OB gave me the Glucose tolerance test.  Isn't this too early?  I thought it can't detect Gestational Diabetes until 28 weeks?

Thanks

Answer
The one-hour glucose tolerance test can be given at 26-28 weeks gestation. That is due to the fact that the insulind requirement is at its highest during that period of time during the pregnancy. If the test shows a value over 40, then the patient is sent for a three-hour GTT. If two of the four values (fasting, 1hr, 2hr, 3hr) is abnormal, it is considered gestational diabetes. If only one value is abnormal, it is considered a carbohydrate intolerance.