Within an hour of eating a midday meal, I become profoundly fatigued. I cannot concentrate, I become muddle-headed and confused, and if I didn t lie down to nap, I think I would fall down. If I do not eat, this doesn t happen. The foods that cause this in its most severe form are eggs and tofu, though virtually all foods cause it. When it occurs, my glucose readings are usually within the normal range. My HbA1c tests are not indicative of diabetes . But a handful of pretzels or a bowl of Grape Nuts will make my levels spike to well over 200. The levels return to normal within two hours.