here is the current guidance from a UK airport website, specifically
mentioning diabetes treatments such as insulin

http://www.blackpoolinternational.com/travel-advice/security-baggage.php

This is as agreed by our DFT (Department for Transport). It mentions
liquids such as insulin needing to be verified as authentic. Blister
packs of insulin cartridges with a patient label would be good, as would
a covering letter from the GP who supplies it. Vials would presumably be
the same. The situation would not appear to have changed much from what
it was up until yesterday regarding diabetic supplies needed in-flight

The Blackpool link is probably the easiest one to post at the moment as
it doesn't wrap and the site isn't congested.

Ratty