Annb
Expert
Since hyperglycemia causes cognitive impairment, wouldn't there also have to be a maximum pre-driving blood sugar? I wouldn't want to drive if I was showing over a 7, though I have cycled with an 8.5 (which turned into a 4.9 mid ride, causing temporary jelly-legs from the adrenergic response) and I'm sure most people would be safe up to 9 as long as they weren't dropping fast.
I understand there's no guidelines on driving while hyperglycemic, and I understand that what I just said is probably completely contraindicated by the evidence.
I haven't heard of any legal guidelines on driving while hyperglycaemic but I know when my BG is exceptionally high, I am not fit to drive. Shaky, problems with focussing vision and probably judgement affected are not unusual in that situation, for me. But I need to be up in the mid teens before I can feel any effect, although others might be able to see something amiss. I have certainly driven with BG of something around 10 or 12 - and not come to any harm. I suppose everyone reacts differently to BG levels, either high or low.