--but if they are giving you a three-hour glucose tolerance test, it would be a good idea if they did so as to get a baseline glucose AND insulin level, given your situation, and then do draws every half-hour and test those for both glucose and insulin.

Often, interesting things like pre-diabetic imparied glucose tolerance are revealed in this way; it is the pattern of glucose/insulin increases/decreases that are often important (i.e, how much insulin is released to counter the glucose challenge, how far does the insulin spike drive down your blood sugar, when do they both normalize, etc.)