In the new book, The Starch Solution, there is a chapter entitled "Salt and Sugar: The Scapegoats of the Western Diet". Keep in mind my copy of the book is a review copy, so everything I'm quoting might change or be removed entirely from the published version coming out in a few weeks.
Anyway, on page 174, under the heading, The Glycemic Index: Not Ready for Prime Time, he talks about the normal increase in blood sugar after meal, and how this raise is so maligned as putting a person at risk for diabetes, thus the frequent advice to avoid foods like potatoes and white rice.
He goes on to say that this fear is unwarranted, that high starch foods have that blood sugar rise because it helps with satiety signaling; it cues you to stop eating.
The interesting part here is the graph, which I'll try to describe:
The left side is blood sugar level, from 0-150. Along the bottom is minutes after intake. It shows two foods, glucose (described as High GI Food) and beans (described as Low GI Food), and charts how the rise in bs happens.
The beans peak at about 100 minutes after intake, causing a rise of blood sugar that appears to hit about 100-105.
The straight glucose, on the other hands, peaks at approximately 40-50 minutes, and raises blood sugar to just about 140 (maybe a little under).
The assumption here is that the graph is for a person of normal health, not a diabetic, and the graph isn't referenced in the text but seems merely to illustrate high versus low GI food effects on blood sugar.
I find it interesting that straight glucose, the example of a "high GI food", only goes up to barely 140, when a simple bowl of cooked (not instant) oatmeal with nothing on it, cooked only with water, sends me to 160-170, and I am regularly tested and do not have diabetes.
I too wish that this would be further addressed. It's certainly frustrating for me, wanting to start the diet yet having mornings like the one I described earlier, where one breakfast had me feeling horrible for hours. When my blood sugar rises and falls quickly like that, I become shaky, anxious, panicky, have difficulty concentrating, nauseous, and headachy, and these symptoms will continue on for quite some time after the blood sugar has gone down.
Right now the breakfast I eat isn't strictly McDougall (though it is vegan and low-fat). It's a protein smoothie, and it's the only thing I've found that I can have (besides animal protein like eggs, which of course I am now trying to avoid) that won't cause these sensations.