We bought our daughter a pink band with a metal tag on it which you could have any text you like engraved on it. So we put her name, type 1 diabetes with insulin pump, and my phone number as the contact. If you just google it loads of sites come up and you can get all sorts of different styles, some personalised to you, some just standard. It depends what you want, how conspicuous you want it to be etc etc. At a later date we also bought her a set of cards, one credit card sized one which she keeps in her wallet, and a couple of key ring ones which she puts on bags and so on. Those just came from Amazon and just had spaces for us to fill the relevant information in. She also has a lanyard with a card on the end which she bought herself for different conditions, just so that she can feel safe when she’s out without me.
The trouble with medic alert is that you have to pay a subscription and I think it’s quite expensive. My daughter so far has never needed any of her IDs, the only time an ambulance was called for her it was not diabetes related and she was at school so the staff were able to give all the relevant details to the paramedics. They are a good idea just for peace of mind but I don’t think you need to spend a fortune on them.