Time of Morning for Glucose Tol. Test
 

Does anyone know if it matters what time of the morning you have the first blood draw for the 2 hr. Glucose Tol. Test. I assumed as long as it was a
12 hr. fast, it wouldn't matter what time you had the first draw, but I read somewhere it should be before 8:30am......don't understand why that would matter.......

Generally, the earlier upon waking, the better--
 

--as daytime activity, especially exercise, can skew the results of the test. When the test is being done, good labs will tell you to stay very still in between draws--no walking around, and certainly no heavy physical activity (and no eating until the test is over--so most labs want to start the test very early to avoid low blood sugar readings from too long a fasting period).

Some tests start before then also! There is a phenomenon called the "dawn phenomenon", which results in elevated sugars, following a big low during the fasting period. They would like to catch you before that happens, since once the liver starts making and releasing glucose for that day your fasting numbers will change even though you didn't eat anything.

A HbA1C is good to have as well, since it gives an average of several months of blood sugar highs. There are charts corresponding to it to estimate the daily average readings.