--even a lot of endocrinologists, order a two hour test with draws before you drink the glucose solution, and then at 1-hour and 2-hours, because that's all they've been taught (or all the lab/insurance will let them do). But this schedule is probably not the best for noticing subtle signs of glucose impairment.

One's glucose level SHOULD go up somewhat from fasting level upon drinking the glucose solution. The keys are how much it goes up and hwo quickly it goes back to "normal" levels, if it does. Most test reports have scales that indicate, at each time period, what indicates "impaired glucose tolerance" and "diabetic", and you're generally allowed a much higher level at 1-hour, labelled as "normal glucose metabolism", than you would be at two hours.

Obviously, if one shoots up to extremely high levels at 1-hour, and stays relatvely high at 2, one has problems. Usually this indicates that one has insufficient insulin to regulate serum glucose. But subtle signs of impending trouble may well be missed by these. One can have "normal" glucose readings and still have metabolic syndrome or insulin resistance--and generally, the scrips aren't written to monitor insulin levels as well as glucose, which can often be revealing, especially if ones starts before the drink with an elevated level of insulin, indicating the body is insulin resitant and needs to produce more to keep glucose in check.

I've written about this a lot, but a several hour test, with more frequent blood draws, and measurement of both insulin and glucose, can often be more revealing--the pattern of the two moving in tandem is often revealing, too. I have mine done for four hours minimum, with glucose/insulin draws at baseilne fasting and then every half-hour. (I admit this makes you a pincushion--and is boring besides, as you can't be physically active during it, which skews the results.) In my case, I start with normal glucose but elevated insulin, have some glucose rise but a bigger insulin spike, which drives my blood sugar leels to lower than fasting in the second-third hour (reactive hypoglycemia); the insulin then recedes and my glucose inches back up to normal. This indicates my body is resistant to insulin effects, it takes more than it should to keep my glucose in check. I'm not diabetic, but I have to watch very carefully, and so I exercise as much as I can, and try to eat in a Zone like manner to keep my glucose levels more stable (and I take R-lipoic for its glucose regulating effects).