What skin problems occur at insulin injection sites?

Two main skin problems can occur at insulin injection sites: lipoatrophy and hypertrophy. With lipoatrophy, fatty tissue under the skin disappears, causing dents in the skin at the injection site. Hypertrophy is the overgrowth of cells, usually fat cells, that makes the skin look lumpy. It can look similar to scar tissue. By rotating the injection site, you can avoid some of these problems. There is also the possibility that some of the problems are caused by the type of insulin you are using.

Lipoatrophy is probably caused by an immune reaction, although its exact cause is not known. Your body is responding to insulin as an injected “foreign” substance. This problem is not common with human insulin. Make sure you are using highly purified insulin, preferably human.

Hypertrophy is not an immune reaction, so you don’t have to change your insulin if you are having this problem. But you do need to change injection sites to avoid this. When the same sites are used over and over again, fat deposits can accumulate in the area. This is also called lipohypertrophy. You may be reluctant to change because injections seem less painful in these areas. This can be true because the hypertrophy can numb the area. On the other hand, injections can sometimes be more painful in these areas. The abnormal cell growth can limit the
absorption of your insulin. Do not inject into the lumps. Insulin action can be restricted by not being able to move through the tissue. Inject away from the lumps and remember to rotate the sites. Ask a member of your health care team to check your injection sites periodically.