From easyJet's regulations
Carrier's Regulations | easyJet.com
Needles
Hypodermic needles are permitted for carriage for medical purposes only. Medical certification must be presented at check-in to permit hypodermic needles to be carried into the cabin.
Passengers travelling with needles must be advised that injections required during the flight must be self-administered. easyJet cabin crew are unable to administer injections under any circumstances.
Diabetics
Injections required during flight must be self-administered. Please ensure that you carry supplies of insulin in your cabin baggage. Diabetic insulin pens will be permitted for travel without medical documentation.