Diabetes Forecast

How Do I Handle Scar Tissue?

I’ve worn an insulin pump on my abdomen for the past 10 years. Recently I had a flurry of “no delivery” alarms and bent cannulas, which I was told was likely the result of built-up scar tissue. I have found a new site for my infusion set. Can I use my abdomen again in the future and, if so, how soon? Joanna Leon, Milwaukee, Wisconsin

Christy L. Parkin, MSN, RN, CDE, responds

“No delivery” alarms and bent cannulas are red flags to check your site. If no insulin is being delivered, diabetic ketoacidosis (DKA) can occur in just a few hours.

What to Know

What many pump users identify as scar tissue is actually insulin lipohypertrophy, a localized thickening of the subcutaneous fat at the injection sites, caused by the fat-promoting effect of insulin. Scar tissue, on the other hand, can build up around an inserted cannula when you use the same site over and over again, and it can lead to a hard bump under the skin after the cannula is removed. Overused sites may have only one of these conditions—or both at once.

If you don’t feel anything when you inject or insert an infusion set, it’s a sign that the tissue is unhealthy. Another clue: erratic blood glucose. Lipohypertrophy is one of the major causes of unexplained highs and lows.

After years of using the same favorite sites, it is common to develop some under-skin scarring and fat buildup. The best way to avoid absorption problems is to rotate consistently and use all available “real estate.” If you have a lump or thickened area, the best treatment is to avoid that site. It is variable as to how long it will take to heal the tissue. You may need to give that area a rest for several months or indefinitely.

Find Out More

In addition to site rotation, it is very important to change your infusion set at least every two to three days. Make a habit to use your clean fingers to palpate your potential infusion sites, gently feeling for lumps and bumps, to determine the tissue health. You may also want to consider using a different type of infusion set to see if that helps. Liposuction, a procedure that removes fat from under the skin, may be used for more extreme cases of lipohypertrophy.


When site issues start to become a problem, it is important to be prepared so you’re not surprised with a “no delivery” alarm. Carry backup insulin in the form of an insulin pen or syringe and vial. Some people take a pump vacation, using multiple daily injections for a few months to give their infusion sites a rest.



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