I've looked on the gov-uk driving-diabetes websites and I've not found anything specific for your case. I assume that you're on insulin and that you currently hold a provisional driving licence.
As far as I can see, and I've looked at the provisional licence on-line application process, there is no obvious place to declare an insulin-dependent medical condition. It does state that you cannot apply for a licence if you are disbarred from driving for any reason [which you are normally not, with Type 1, on Insulin]. I think you should download ASAP form DIAB1 from the gov.uk website, complete and post it to Swansea. They should deal with it and, in the meantime, I hope you pass your driving test.