Lipohypertrophy: Lumps From Repeated Injections
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[Glossary · Injecting]

Lipohypertrophy

Also called injection lumps, fatty lumps at injection site, LH · Reviewed

Definition: Lipohypertrophy is a rubbery lump of thickened fat under the skin that forms where injections are given over and over in the same place. A 2026 review calls it the most common complication of insulin injections. Medicine injected into it can absorb unevenly, which makes doses less predictable.

How common it is

In a 2013 study of 430 people injecting insulin, a nurse found lipohypertrophy in 64.4% of them. A 2026 meta-analysis of 18 studies and 7,139 insulin users found it in 70.5% when ultrasound was used to look for it, which picks up lumps that are hard to feel.

The 2013 study tied it most strongly to not rotating sites. Of the people who rotated correctly, only 5% had it. Reusing a needle more than 5 times also raised the risk.

Why it matters when you track doses

A 2024 meta-analysis of 37 studies found that insulin users with lipohypertrophy had more unexplained low blood sugar, more swings in blood sugar, an HbA1c about 0.55 points higher, and used about 7.7 more units of insulin a day than those without it.

The Lantus label says not to inject into these areas, and notes that a sudden move from an affected area to healthy skin has been linked to low blood sugar. If your log shows the same dose working differently from week to week, the site column is one of the first places to look.

Almost all of this research is in insulin users. We found no prevalence data for people injecting GLP-1s or research peptides, so the numbers above should not be read as their risk.

What helps

  • Rotate sites with each dose, as GLP-1 labels say.
  • Use a new needle for each injection.
  • Log the site, so a favorite spot does not quietly become the only spot.
  • Ask your prescriber to check any lump that stays.

Read more on Dose Track: Why injection site rotation matters

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Injection site rotationInjection site rotation means moving each injection to a different spot instead of using the same patch of… Subcutaneous injection (SubQ)A subcutaneous injection (SubQ) puts medicine into the layer of fat just under the skin, above the muscle.… Injection site reactionAn injection site reaction is any change at the spot where a shot went in: redness, swelling, itching,… BioavailabilityBioavailability is how much of a dose, and how fast, gets absorbed into the body where it can act. The FDA…

Frequently asked questions

What does lipohypertrophy feel like?+
Usually a soft or rubbery raised lump under the skin at a spot that has had many injections. Ultrasound studies find more cases than touch alone, so some are hard to feel.
Does it go away?+
The sources we checked do not give a reliable timeline. The Lantus label says not to inject into affected areas, and a prescriber can check any lump that stays.
Why does injecting into a lump matter?+
Absorption from the lump is uneven. In insulin users it has been linked to more blood sugar swings and higher insulin use.

Sources

  1. Zhang et al. BMC Public Health 2026 (ultrasound-detected lipohypertrophy, meta-analysis of 18 studies). PMID 41593584
  2. Blanco et al. Diabetes Metab 2013 (prevalence and risk factors of lipohypertrophy in 430 insulin users). PMID 23886784
  3. Mader et al. Diabetes Technol Ther 2024 (lipohypertrophy, glycemic control and insulin dosing, meta-analysis). PMID 38215209
  4. Lantus (insulin glargine) US prescribing information, DailyMed

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