Pancreatic islet transplantation has become a widespread treatment for certain cases of type 1 diabetes in many countries throughout the world — but not in the United States, which lags behind in offering the procedure due to what many doctors consider misguided regulatory barriers, according to a presentation at the 81st Scientific Sessions of the American Diabetes Association (ADA) earlier this summer.
In type 1 diabetes, a person’s immune system mistakenly attacks groups of cells in the pancreas known as islets, which include the cells responsible for producing insulin. As this attack ramps up, fewer cells are able to produce insulin, eventually resulting in little to no insulin being produced. In islet transplantation, pancreatic islets are extracted from a deceased organ donor, processed and purified, then infused into the recipient through a catheter (small tube) inserted through the abdomen into the liver.
Islet transplant recipients need to take drugs designed to stop their immune system from attacking the donor islets. Once an islet transplant occurs, the transplanted islets begin producing and releasing insulin almost immediately, but it can take time to reach full islet function and insulin production. Many people with diabetes require two or even three islet transplants to achieve independence from injected insulin, according to the University of California San Francisco. The procedure is generally reserved for people with type 1 diabetes who experience hypoglycemia unawareness, putting them at risk for coma or even death if their blood glucose level drops unexpectedly.
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Islet transplantation has slowed in the United States
In the ADA presentation, experts in islet transplantation from around the world discussed why the procedure has slowed in the United States relative to other countries. Only one center in the United States has performed more than 100 islet transplants between 2000 and 2020 — the University of Miami Miller School of Medicine. But in the last two years, zero islet transplants have been performed there. Meanwhile, at least 11 centers in Canada, Australia, Europe, and Asia passed the 100-transplant milestone in 2020.
There is one overwhelming explanation for the U.S. slowdown in islet transplants — the insistence of the Food and Drug Administration (FDA) that it has the authority to regulate islets used on the procedure as cell-based therapies, or biologic drugs. This is the case because a 1984 law called the National Organ Transplantation Act, which regulates organ transplantation and protects it from commercialization, never saw its rules updated after an amendment that added subparts of organs — like pancreatic islets — to the definition of organs under the law. As a result, organ transplant networks in the United States can only participate in islet transplants as part of clinical studies.
In contrast, regulations in other countries treat islet transplants the same as other organ transplants, allowing them to occur in normal practice, not just as an experimental treatment being studied. Earlier this year, a consortium of groups with an interest in type 1 diabetes petitioned the U.S. Department of Health and Human Services to update its rules on organ transplantation to allow islet transplants, but this effort was unsuccessful. And while islet transplants are classified as experimental, health insurance plans won’t cover them, as they cover transplants of full organs.
The bottom line, presenters agreed, is that until federal rules are updated to include subparts of organs in the definition of organ transplants, islet transplantation in the United States will face enormous barriers that prevent large numbers of people with type 1 diabetes from benefiting from the procedure — resulting in avoidable hospitalizations and deaths brought on by hypoglycemia unawareness.