I agree with you LesleyB, there's no real reason for blood sugars to run high after a hypo unless you overcorrect with your Mars Bar. If you get enough fast acting carbohydrate down you to raise your blood glucose by 3 or 4 mmol/l, then that's all you need. There's little worse than a hypo, followed by a hyper, another correction shot, then the cycle begins again.....
Adrenaline and cortisol will raise your blood sugar too, the old flight or fight thing, but not enough to send you into double figures. Not in my experience at least.
All the best,
fergus