■ Site selection Site selection is based on the different rates of insulin absorption. The most predictable area for injection is in the abdomen, followed by the outer back areas of arms, the outer thighs, and the buttocks.
Places to avoid injecting insulin include: the skin in the two-inch radius around the umbilicus (navel); moles or scars, where absorption will not be as consistent; any part of the arm other than the outer back area where the highest concentration of fat is located; and the inner thighs, since thighs may rub together when walking and cause soreness at injection sites.
Some clinicians recommend injecting in the same general area for one to two weeks, putting the needle in a different spot, and then moving to another area of the body. It also is important that patients not inject in areas that are going to be exercised, since increasing blood flow to the skin of a particular area increases the rate of absorption.