Identifying the Achilles' Heel of Insulin Pump Technology
Researchers utilized optical coherence tomography (OCT), a non-invasive technique, to monitor blood flow and inflammation around the pump infusion sites. This allowed them to assess the speed of insulin absorption, with higher blood flow indicating quicker absorption. Skin biopsies were collected from these sites for analysis ().
"No one had done a human study on what happened to the skin under these sites until now," said senior author Dr. Irl Hirsch, professor of medicine, Division of Metabolism, Endocrinology, and Nutrition at the University of Washington School of Medicine. He is also the diabetes treatment and teaching chair in the Department of Medicine.
Limitations in Insulin Pump Therapy
The advances in insulin pump therapy have freed up patients from the daily routines of injections and, when connected to continuous glucose monitors, can give them precise dosing based on their blood glucose levels. However, there is an Achilles' heel of the therapy that has not been addressed, said Hirsch.‘A groundbreaking study is now investigating the concern of patients facing the issue of "running out of real estate" as their pump sites become fibrotic, irritated, and less efficient in delivering insulin. ’
"It really doesn't matter how good the technology is," he said. "We still don't understand what is happening with the infusion sites, much less fix it."
This study, performed between 2020 and 2022 (paused due to the pandemic) enrolled 30 participants from the UW Medicine Diabetes Institute. It was the first such step to answer both these questions.
The study participants were divided into two groups: those patients using insulin pumps for 10 years or less, and those using pumps for over 20 years. Researchers expected to see more pathology - thickening of skin, damage to the subdermal layer, inflammation - in the group using the pumps for 20 years or more. That's not what happened.
"We found that the pathology, to our surprise, was no different when short-term user results were compared with long-term users," he said.
Both groups had high levels of eosinophils, disease-fighting white blood cells that usually appears in the blood to fight allergies. Generally, they assist in healing the skin and creating fibrosis.
"This is the last thing you want at an infusing site," Hirsch said.
"From a bigger point of view of fibrosis, inflammation and eosinophils, we saw all this in both groups, but we don't understand yet why it's happening," he said. "How much was the catheter or the insulin causing the irritation around the sites? How much was it from the preservatives or is this because of the insulin pump itself?"
In addition, some patients move the injection site from place to place because of irritation, and other patients have no irritation at all. Yet, researchers don't know why.
All these questions need to be answered in future studies, he said.
"Ninety-three percent of those in the study complained of itching, which points to eosinophils being present, but we are also going to look at metabolomics," he said. "The real goal of all of this is to minimize skin damage and improve the experience for our patients.
Reference:
- Evaluation of Insulin Pump Infusion Sites in Type 1 Diabetes: The DERMIS Study - (https:diabetesjournals.org/care/article-abstract/doi/10.2337/dc23-0426/153369/Evaluation-of-Insulin-Pump-Infusion-Sites-in-Type?redirectedFrom=fulltext)