There is an initial blood sugar spike--and it may be a big one--but after that the overproduction of insulin drives blood sugar down to levels below those that individual usually has in a fasting state, thus the hypoglycemia. Levels usally stabilize as the insulin pulse recedes in response to the lower blood sugar, but this whole stabilizing process may take a total of 2-4 hours, and people can have lots of interesting symptoms in that time.

Much of my family is afflicted with this--my brother worst of all, apparently--although I was the first one to monitor the pattern by getting a 5-hour glucose tolerance test, with glucose AND insulin levels taken at baseline and every half-hour. We all show signs of insulin resistance in having relatively high baseline insulin levels, and we all tend to accumulate belly fat in that typical male metabolic syndrome way.