I think this a worthy discussion. I've been looking through all my old First Aider stuff, and looking at St John's Ambulance things to get more updated info and it would seem that if you collapse in the street the first responder, who is aware of first aid methods will be concentrating on making sure that the person is breathing and in the recovery position, baring in mind that for an obvious heart attack the recovery position is slightly different. It might be that when checking for breathing that breath smell might be noticed, fruity pear drops or nail varnish which would indicate a hypo. Otherwise it could be a while before an ambulance arrives.
The wrist sounds like a good idea because that's where the pulse can be checked although even that is no longer in advice to first aiders. Interesting dilemna.