Pump
I had that happen with three in a row in Dec, 2007. I thought it was my pump, but it turned out to be scar tissue. I had used my upper abdomen for injections for many years and a build up of scar tissue beneath the skin's surface had formed. There is almost no absorption of insulin on that part of my body. Very high blood sugar can occur when placing an infusion set in scar tissue.
I was advised to use other body sites and to rotate sites so i would not have additional scar tissue. Now I rotate between my lower abdomen and my upper legs, where there is fatty tissue. There has not been anymore problems except when I place my set too close to my upper abdomen. There is permanent scar tissue there and I can never use my upper abdomen again.