Understanding Lipohypertrophy How To Avoid Injection Site Bumps

Are you wondering what those lumps are where you inject your insulin? Is your blood sugar high one day and low the next, despite eating the same thing and nothing else really changing? Does it seem like your insulin isn’t working? If these questions sound familiar, you may have something called lipohypertrophy or a “lipo.” Lipos are areas of fatty tissue and scar tissue that develop under the skin.

Lipos are more common in individuals who take insulin versus other types of injections (e.g. Ozempic®, Mounjaro®, etc.). This is due to insulin being a growth factor, which can lead to an increase in fat cells at the injection site.

Reusing needles and not rotating injection sites (giving insulin in the same small area repeatedly) are the 2 most common risk factors. Other factors include the number of insulin injections per day you are using, the amount of insulin administered in 1 injection and how many years you have been using insulin.

Lipos can increase blood sugar and A1C. When injecting into a lipo, insulin absorption can vary: it may not absorb as well or absorption may be delayed. This variability in absorption can lead to both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) as the action of insulin is not matching the rise in blood sugar.

When insulin absorption is reduced, insulin needs will increase to bring blood sugar to target. The cost of insulin also increases due to higher insulin doses. When another ‘non-lipo’ site is selected using this higher dose, insulin will be absorbed properly, increasing the risk of hypoglycemia. Regulating insulin doses that have unpredictable absorption can be very challenging.

For those living with type 1 diabetes, lipos can increase the risk of diabetic ketoacidosis.

Red flags that you may have a lipo include not thinking about where you inject your insulin, having a favourite area to inject insulin as it hurts less, or having unexplained hypoglycemia (low blood sugar that is not caused by delayed or missed meals, exercise or taking too much insulin/medication). It is best to assess for lipos in a well-lit area while either laying down or standing (standing in a shower works well).