I travel frequently, and have never had an issue. Get a letter from your DSN or your GP, but round here the GPs charge and the hospital doesn't. This is just in case you're asked but 99 times out of 100 if asked just say your diabetic and everything will be fine. Just remember to put all your insulin (including that the pens) in the little plastic bag which is removed from your hand luggage and you'll have no problems.
Hope you have an excellent trip! :wave: