I don't think lucozade or glucojuice (or other hypo treatments) should be generally exempt because there would be a risk of abuse. Although I can't really see the cool kids deciding to save 8p and swigging on lucozade instead of Coke!
Ideally, I would like to see an exemption or rebate scheme for insulin dependant diabetics buying hypo treatments that are caught by he sugar tax. But I absolutely appreciate that the costs of such a scheme would probably make it counter productive.
I understand that funds raised from the sugar tax will go to funding healthy lifestyle education in schools. So what I would like to see is the money (or a percentage of the money) raised to the sugar tax from products widely & traditionally used as hypo treatments going to fund education for insulin dependent children on how to manage diabetes and exercise. I think that would be a nice compromise position that wouldn't undermine the public health aims of the tax, would hopefully not be costly to administer and would mean that I wouldn't feel like I was being unfairly penalised for having to purchase hypo treatments.
Just an idea