We currently have a student with the same condition. When they enrolled, a lot of paperwork was sent to me by the hospital recommending 25% extra time AND rest breaks. After a discussion with the student, we established that only rest breaks would be needed and yes, they would need to monitor their glucose levels on a device. We could not find any reason to give extra time in addition to this as the student has no other difficulties. I believe that there is a specific app for monitoring that does not require Wifi/data, but, I passed that aspect of things to our Exams Officer to clarify the rules around this and what the procedure is to avoid any malpractice. Therefore I have only applied for, and written a Centre File Note to confirm rest breaks are needs to allow the student to respond to any issues with blood sugar – they may need to leave the room, have some sweets etc until their blood sugar returnes to normal. I
Maybe you can askf for something similar from their doctor/hospital?
I hope this helps!