--a two hour glucose tolerance test with only glucose measurements is inadequate; the blood draws stop too soon and are too spaced out and one might miss the pattern of insulin release and its relationship to glucose levels, as they work by a mutual feedback mechanism.

if you can get the doctors to sign off (and you can certainly use some of the literature on pre-diabetes available through links on Neurotalk to buttress the argument), have them do a 4-5 hour glucose tolerance test with a baseline draw for both fasting glucose AND insulin levels before the drink and then draws every half hour for both glucose and insulin. Though I admit this is long and boring and makes one feel like a pin cushion, the fasting insulin level is an important number--one wants to know if one's "normal range" fasting glucose number is due to increased insulin production, due to tissue insulin resistance--and then one wants to see how much insulin is produced by the challenge. An overproduction of insulin to the modest glucose of the drink points to insulin resistance, the first stop towards diabetes, and if this overproduction is large enough one may well see a drop in glucose to hypoglycemic levels in the second to third hour; that may well cause the insulin production to "let up" and allow glucose levels to go back to more "normal" levels--but this is often missed if the draws are stopped too early, or if they are not done frequently enough.