Hi there
My son was diagnosed in the last few months before his GCSEs. For him, our school weren't quite so good. I phoned and spoke to the exams officer in advance and was assured everything would be fine. They said they would prepare him a hypo pack from the supplies we provided to the school nurse anyway, he could take his meter in, and the invigilator would have a note of his seat number. They would also place him near the door in case he needed to exit in a hurry. They said if he needed time out to test and treat a hypo, the clock would be stopped for him, and he could have extra time added at the end to finish to allow for the time he was out of the exam.
Our school would not allow our son to take his own hypo stuff in, except for his meter. THEY made up a hypo pack which they made from things we had provided anyway, kept in the nurse's room normally, but unfortunately for him this kit was labelled in big bold capital letters 'XX - Diabetic Hypo Pack'. So for my lad, who had not come to terms with it and was very secretive about it, he was horrified to see this, his name and condition on a pack placed at the front of the exams hall. There was nothing he could do of course, but get on with his exams. He was told if he felt unwell he was to raise his hand and wait for an invigilator to go to him. He would then be escorted out of the hall, being allowed to collect the hypo pack on the way, then could treat it and come back and finish his exam, staying behind to make up any lost time.
Unfortunately for my lad, this was way too embarrassing. He started down the slippery slope of skipping insulin before exams, to avoid any chance of a hypo. I know he just wasn't going to cope with the embarrassment of being escorted out of the hall with everyone watching. Just beware of that.
I would urge you to speak to your school's exams officer as soon as possible to see what they are prepared to do, but at least if this is only mocks, it is a chance for a good practice run. One thing we did learn, is that if your son takes exams in November or March and doesn't get good results because of diabetes related problems, they aren't prepared to tweak those results as their attitude is that the student can re-sit the exams in the summer. If it is the final May/June exams and they are in year 11, then it's a different matter and they may be able to tweak results by 10 or 20%, can't remember which.
My lad took some science modules in the January after an end of December diagnosis, but actually did better then than in the summer when he opted for retakes!
I would urge you to speak to your school as a matter of urgency, having some idea of what you would like to achieve first, and see what they are prepared to offer. I have heard of others being offered a separate room but my lad would have seen that as being singled out and didn't want it. Teenage boys can be very sensitive about things like this, so you need him to feel as comfortable as he possibly can with the arrangements.
Good luck!
Tina