If you give yourself insulin injections, you might eventually see or feel hard, lumpy areas under the skin. This condition is called lipohypertrophy, and noticing it for the first time can be worrisome or even downright scary. What is lipohypertrophy? What causes it? And can it be prevented?
What is lipohypertrophy?
Lipohypertrophy occurs when fatty lumps appear under the skin. Initially, lipohypertrophy can start as thickened skin; over time, the following characteristics may appear:
- Small, hard or large, rubbery areas ranging from the size of a pea to a tennis ball.
- A surface area over one inch in diameter.
- A firmer-feeling area compared to other places on the body.
Sometimes lipohypertrophy is present without lumps; the area is flat, in other words. A healthcare provider can confirm the presence of lipohypertrophy by deeply palpating the skin. Ulltrasound can also pick up lipohypertrophy.
Symptoms, however, don’t include pain, redness or bruising. If you have these symptoms, you could have an infection or an injury, so be sure to let your healthcare provider know.
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Why does lipohypertrophy occur?
The main cause of lipohypertrophy is giving multiple injections in the same area over an extended period of time. Since insulin is an “anabolic” hormone (meaning, it promotes the storage of glucose, amino acids and fat), it can lead to the buildup of fatty tissue at the injection site.
People with type 1 and people with type 2 diabetes who inject insulin are at risk for developing this condition. In one study, published in the journal Diabetes in 2019, 62% of the subjects had lipohypertrophy. Another study in the Journal of Caring Sciences in 2018 found that the prevalence of this condition in patients with type 2 diabetes was 44%.
Risk factors: Who is more likely to have lipohypertrophy?
Since lipohypertrophy occurs as a result of repeated injections into the same area, anyone who administers an injection subcutaneously (meaning, injecting into the tissue area just under the skin) is at risk. If you use a non-insulin injectable medication, such as a GLP-1 receptor agonist (Victoza, Byetta, Bydureon, Tanzeum, Trulicity, Adlyxin, Ozempic, Rybelsus) or if you insert an insulin pump infusion set or a CGM sensor, you can be at risk for lipohypertrophy, too.
Other risk factors for lipohypertrophy include:
- Longer duration of insulin therapy
- Taking insulin injections four or more times daily
- Taking higher doses of insulin
- Taking both mealtime and long-acting insulin
- Reusing needles
- Using a longer needle length (greater than 5 mm)
- Not rotating, or changing, injection sites
- Having a high A1C
- Having frequent episodes of hypoglycemia (low blood sugar)
- Being overweight or obese
Why is lipohypertrophy a concern?
You may not be happy to see or feel lumps under your skin (not many people would be!). But appearance aside, lipohypertrophy can cause insulin to be absorbed erratically and unpredictably. As a result, you may notice more high and low blood sugars despite taking your insulin as prescribed, watching your carbs, staying active, etc. You may end up having to take more insulin, too. Managing diabetes, then, can become a whole lot harder.
Does lipohypertrophy go away?
Fortunately, those lumps and bumps do get smaller and will go away. But be patient, as it can take many weeks or even months to notice an improvement. In extreme cases, areas of lipohypertrophy can be surgically removed. Studies also show that liposuction may be useful, as well.
Can you prevent lipohypertrophy?
The answer is yes! How? Rotate, rotate, rotate — your injection sites, that is. Remember that using the same injection site, say, the left side of your abdomen, all the time is what causes lipohypertrophy in the first place. By switching things up, you can prevent this from happening.
Your healthcare provider or diabetes educator will likely talk with you about “rotating your injection sites.” Common injection areas include:
- Abdomen, or stomach (stay at least a finger-width away from the belly button)
- Thighs (upper, outer part of the thighs)
- Buttocks (upper external part of the buttocks)
Rotate your injection site with every injection, and inject at least one finger-width away from your previous site. Try not to use the same injection site more than once every four weeks.
What else can you do to prevent lipohypertrophy?
- Avoid injecting into areas of lipohypertrophy.
- Use a new needle for each injection.
- Use a shorter insulin needle. The shortest insulin pen needle available is 4 mm (millimeter); the shortest syringe needle is 5 mm.
For more information about insulin injections and site rotation, download the Insulin Injection Know-How sheet from the Association of Diabetes Care & Education Specialists here.
Finally, at each regular office visit, ask your provider to check for areas of lipohypertrophy, especially if you notice more erratic blood sugar levels.