Hi Lauren, just try and do your best, and try and get some sleep tonight. You may find that, once the questions are there in front of you things will come back to you - it's too late just now to learn anything new, so try and take it as it comes. Stress makes my levels go higher, but you may be different. Be sure that there is a proper arrangement for you to speak to an invigilator during the exam if you feel at all poorly - this is not your fault and they should do everything they can to help you through it. Remeber to take your meter and some hypo treatment in case you need it. Remeber also, that if you go low, they should not expect you to continue for at least 15 minutes until you have recovered sufficiently.
I do hope that things go well, and will be keeping my fingers crossed for you!🙂