--into the whole endocrine picture, not just that involved in the glucose/endocrine dance.

The response people have to a given amount of glucose will vary widely--both due to individual differences such as muscle mass, amount of body fat, genetics (especially, as Kmeb alludes to, alimentary transit time) . . .and it can vary quite widely in an individual from situation to situation.

Moreover, the picture is tied in to the action of other hormones, as well--cortisol especially (this tends to make excess glucose get deposited as fat, particularly in the abdomen and hips, when it is not utilized--and this contributes to the insulin resistance cycle, as muscle utilizes much greater amounts of glucose--and thus insulin--for its energy needs than fat cells). And yes, adrenaline (epinephrine) release can be triggered by sudden stress, such as a drop or spike in glucose levels, and it tends to itself have a very seesaw effect. The sympathetic nervous system that sets off the adrenals is the "fight-or-flight" mechanism of the body, and the adrenal signals cause the liver to release glycogen, which is converted to glucose. In essence, the body is preparing for rapid action, and thinks it needs fuel. If this fuel is not consumed in action, however (and how often is it in the modern world), the glucose hangs around in the bloodstream long enough to percipitate an insulin reaction, followed often by a major plunge in serum glucose concentration, resulting in hypoglycemia and fatigue. (Bottom line--unreleased stress is not good for your endocrine system and a lot of other things.)

It's a very complicated picture even in "normals"--and those of us with neural problems, with the signal disruptions that can cause, complicate it still further.

Oh--quick answer, Mel: they can do insulin levels with the same blood samples as they're doing the glucose levels with; no other modificiations in the test are necessary. Thing is, docs have to include insulin levels in their instructions; labs don't do this automatically (insurance costs, again)--though they probably should; the patterns of glucose level and insulin level, examined together, can often provide more insight than looking at either one alone.