I always carry my meter (Freestyle Flash) and glucose tablets. I also keep a bottle of glucose tabs in my car but in the summer time they get really hard ... but they still work. Would rather have them work and taste bad, than to not have anything at all.
I wear a pump so I don't carry any other supplies - although I know I "should" always have a spare infusion set on me ... :/ I actually thought about posting this question a couple of days ago. I carry all of my supplies (so if I have to grab 'n go) at home in my daughter's Libby Lu pink draw string bag. Kinda funny but it works. That's where I keep all of my "at home" supplies - injectors, CGM transmittor charter, extra batteries, etc. It's easy to pack for trips that way, too. I know all I need is in there, except for extra insulin which I keep in the fridge.