It might be a good idea for you to go and check out the Type 1 forum for threads on how to effectively deal with hypos (basically, 10-20g of fast acting carbs eg lucozade, wait 10mins, make sure your sugars are 4, then 10-20g or so of slow acting carbs - a thick slice of bread/toast, 2 digestives, a packet of crisps, or 6 squares of milk chocolate etc). NB milk chocolate is good because fat slows down the absorption of glucose - so actually, milk chocolate is slow-release. Oh how I rejoiced the day I learnt that :lol:
When I was last at 2.5, 2 weeks ago, I truly thought I was dying (even though I have been lower) so it's no surprise you feel rubbish at that level - look up neuroglycopenia on wikipedia, it hits you around the 2.8 mark. Plus the DVLA, when you're diagnosed with Type 1 and you have to get a 3yr license, inform you that you are not legally allowed to drive for 45 minutes after your sugars are above 4 again as it takes that long for the brain to recover. I find the lower I go the longer it takes to feel better and it can even be hours or, when I once hit 1.9, it took 24 hours.
When hypo, the idea is to immediately raise your sugar hence lucozade, coca-cola, lemonade etc being good straight off (not a whole can - about half a can). The crisps (or whatever slow acting carb you choose) that you eat once your levels are above 4 are to ensure you don't go hypo again, because the quick acting stuff can disappear very quickly from your system. One of you stated you didn't know why lucozade and crisps seemed to work - it's because they both contain carbs, which is what you need to raise your levels. The salt's got nothing to do with it though! Sorry if this is a bit rambling but the first rescuer's going down in the capsule to get the Chilean miners so I'm half typing, half watching telly and not concentrating properly.... oh, and look up the Glycaemic Index - I imagine you need to generally aim for foods that release nice and slowly into your system (I don't mean during hypos, I mean normally - it might help prevent some hypos for you). Basically it's a way to grade slow acting and quick acting carbs in foods.