Last time I flew I took a GP letter AND a copy of my prescriptions which you get when you collect your prescription.
All prescriptions had the pharmacys sticky label on with my name and date issued.
I rang the airline before travelling and gave my details and told them I would be carrying meds including needles on the flights out and back.
At check in I advised staff I had needles etc and showed them the GP letter.
Went through the X Ray machine with Libre no problems.
I decided to get the GP letter and all meds with the labels on (had to reorder a few meds which I'd already removed the pharmacy labels) before going through to make sure there were no issues.
Might be overkill but it's minimal effort which could save potential issues,delays,expense and inconvenience.