Iv'e never injected into muscle , but went through a few big veins at first, pulled out the needle and it just bled lots resulting in me panicing (as I had read that the insulin works really fast, if injected into a vein) so I stuffed my face with anything I could get my hands on and ended up with mega high BGs , I survived though, and enjoyed the food :lol: . I can avoid this now as I insert the needle slowly and if I hit a big vein it feels springy like the needle is hitting an elastic band so I just pull it out and do it somewhere else(I hit em so many times I can feel the difference now) I still occasionally go through little ones but they dont bleed much, just leave little bruises.