Insulin-derived amyloidosis

Insulin-derived amyloidosis, also known as insulin ball, is a subcutaneous amyloid mass at the site of repeated insulin injections. Because patients may find injections to be less painful at the site of the amyloidosis, some inject directly into them instead of at a new site. Insulin absorption at sites of insulin-derived amyloidosis is about one-third of that compared with other sites. Insulin-derived amyloidosis is uncommon and is often misdiagnosed as insulin injection--associated lipohypertrophy, which occurs in as many as 50% of patients. Ultrasonography, CT and magnetic resonance imaging may be used to distinguish between the 2 entities; however, a definitive diagnosis can only be made histologically. Both conditions can be managed by rotation of injection sites. Amyloidosis often regresses slowly after insulin injections are stopped, whereas lipohypertrophic lesions tend to resolve more quickly. Patients presenting with unexplained, worsening glycemic control should have their injection sites examined and blood glucose levels monitored regularly.