Hi Jordan, This is not an allergy like some have suggested but some sort of sensitization that happens in your tissue. I have been type 1 diabetic for almost 30 years. I started injecting in my stomach, then my thighs and now my arms and rear end. I switched sites mainly because after a few years of injecting in one area the lumps, irritation and inflammation appear. Now my arms and rear end are aching and I don't know what to do next. I use Levemir and Novorapid. Not sure if one causes more irritation than the other. I use 8mm novolin needles. The short ones don't work for me as I am a bit overweight. (Or a lot, depending on POV). Try injecting on the upper part of your buttocks. It's not that difficult. It's a large area too and you should be able to inject for years before it gets sensitive.