If you join Medic Alert once they have your details they will know what to engrave, containing the relevant information held on their files. The disc will be engraved with your main medical condition(s), a personal ID number and the 24 hour emergency telephone number.
"A 24 hour emergency telephone number which accepts reverse charge calls that allows emergency and medical professionals to access their details from anywhere in the world in over 100 languages" [q.v medicalert website]
Consider this, you have a hypo and fall unconscious in a public place, if you are lucky and are wearing an identifying emblem an ambulance is called rapid treatment provided.
However if there nothing to readily identify you as a diabetic, people think you are a drunk and the police are called, or more likely left alone, with the subsequent delay in treatment.
First aiders/responders are trained to look at your wrists and neck for an emblem, on an unconscious/non responsive casualty
I pay ?25 a year for this piece of mind, as far as I am concerned, it is priceless.