I don't have a special D bag. I fill my pump reservoir with 140U Novorapid (enough for 3 days) at once, using a pen cartridge, so when I fill it for the first time I put the cartridge with 160U left back in my back, and after I fill it the second time I put the cartridge with 20U left back in my bag. That way, I always have some fast acting insulin for an emergency. I don't carry a spare site most of the time, because I'd just give myself a bit of fast acting with the pen every hour in case of emergency. Other than the pen, I carry my meter and glucose tabs. Sometimes glucose gel. And glucagon. I never used to carry glucagon, but I told my friends about its existence and all of a sudden they all wanted to learn - so six of my best friends are now glucagon trained, and there is a point to carrying it around with me. Since I'm hypo unaware mostly, it does make me more comfortable to have it with me, just in case.