--can actually be a sign of pre-diabetes or impaired glucose regulation.

Often, in those whose tissues are becoming more resistant to the effects of insulin (with concomitant raised fasting blood sugar levels), it will take more insulin to maintain relatively stable glucose readings. Then, when a person undergoes glucose challenge (either in testing or just eating a meal), the pancreas will overcompensate by producing more insulin than necessary, driving blood sugar levels down to hypoglycemic levels a few hours after eating. People may or may not have symptoms of low blood sugar then, but the extreme swings in both blood sugar levels and insulin levels are not good for body tissues in general, or for nerves in particular.

One of the ways this can be discovered is to have a much longer glucose tolerance test with more frequent draws, such as a 5-hour glucose tolerance test with baseline glucose AND insulin levels measured and then blood draws at .5, 1, 1.5, 2, 2.5, 3, 4, and 5 hours. It is the cycles of blood sugar levels and insulin responses that are instructive--typically, people prone to this have elevated fasting insulin levels to start and then show an exaggerated insulin spike to the glucose challenge somewhere around 1-1.5 hours, with a corresponding big dip to initially raised glucose levels (which may or may not reach diabetic levels), which drives down glucose levels in the 2-2.5-3 hour area. Eventually, insulin levels recede and glucose levels become more normal--that is why one needs the 4/5 hour draws, to confirm this.

And, Mrs. D, thanks for fixing the links.