The results of a phase 3 clinical trial are being hailed as a "breakthrough" in the treatment of type 1 diabetes, after finding that transplantation of islet cells - clusters of cells in the pancreas that contain insulin-producing cells - prevented potentially life-threatening reductions in blood sugar among patients with the disease.
Study co-author Dr. Xunrong Luo, associate professor of medicine and surgery at Northwestern University Feinberg School of Medicine in Chicago, IL, says the findings show that islet cell transplantation is a viable treatment option for type 1 diabetes patients who have severely low blood glucose levels, or hypoglycemia.
What is more, the team says the findings suggest islet cell transplantation could eliminate the need for lifelong insulin therapy for people with type 1 diabetes.
The researchers recently published their results in Diabetes Care - a journal of the American Diabetes Association.
Type 1 diabetes accounts for around 5% of all diabetes cases in the US. It occurs when beta cells within the islets of the pancreas are unable to produce insulin - the hormone that regulates blood glucose levels by promoting transportation of glucose from the bloodstream to other cells, where it is used for energy.
Individuals with type 1 diabetes require lifelong treatment with insulin, either through multiple daily injections with an insulin pen, syringes or an insulin pump, which helps regulate blood glucose.
However, even with treatment, some people with type 1 diabetes continue to experience fluctuations in blood sugar levels.
Hypoglycemia and its life-threatening complications
Hypoglycemia occurs when blood sugar drops to abnormally low levels, normally below 70 mg/dL. Early warning signs of hypoglycemia include shakiness, sweating, confusion, blurred/impaired vision and fatigue.
However, some people may experience no warning signs at all - a condition known as hypoglycemia unawareness. Such individuals are more likely to develop severe complications as a result of hypoglycemia, including seizures, coma and death.
"Even with the best care, about 30% of people with type 1 diabetes aren't aware of dangerous drops in blood glucose levels," notes Dr. Griffin P. Rodgers, director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which helped fund the new study.
While continuous glucose monitoring systems or behavioral therapies can prevent such complications for some type 1 diabetes patients who experience severe hypoglycemia, not all of them benefit.
This highlights the need for alternative treatments, and Dr. Luo and colleagues believe they have identified one: islet cell transplantation.
How does islet transplantation work?
For their study, the researchers enrolled 48 patients with type 1 diabetes who, despite receiving care from a diabetes expert or endocrinologist, had continuous hypoglycemia awareness and often experienced complications as a result.
All patients underwent at least one transplantation of islet cells. This involves implanting healthy pancreatic islet cells from a deceased donor into the recipient.
The transplantation procedure is minimally invasive; the donor islet cells are purified, processed and infused into the portal vein of the recipient - the vessel that transports blood from the intestine to the liver - through a small catheter that is inserted into the recipient's abdomen.
Once transplantation is complete, the beta cells within the implanted islet cells begin to produce insulin soon after. However, it takes longer for the new islet cells to become fully functional. Until then, patients will need to continue insulin therapy for blood glucose control.
In this study, subjects who were still taking insulin 75 days after initial transplantation underwent a second transplantation. A second transplant was required for 25 participants, while one subject underwent three transplantations.
'A new era of breakthrough therapies for type 1 diabetes'
The blood glucose levels, hypoglycemic awareness and incidence of severe hypoglycemic events among participants were assessed 1 and 2 years after transplantation.
After 1 year, the researchers found that 88% of the participants had near-normal glucose levels, their hypoglycemic awareness had been restored and they had experienced no severe hypoglycemic events. These results persisted for 71% of the participants 2 years after transplantation.
After 1 year, insulin therapy was no longer required for 52% of the participants.
Commenting on their findings, Dr. Luo says:
"Islet transplantation is heralding a new era of breakthrough therapies for type 1 diabetes that isn't controlled by conventional treatments.
These results make a clear case for islet transplantation as a viable treatment option for individuals with type 1 diabetes complicated by severe hypoglycemia. Our research found that transplanted islet cells provided glycemic control, restored hypoglycemia awareness and protection from severe hypoglycemic events."
The need for lifelong immunosuppressant drug use a concern
The researchers note that five participants experienced transplant-related complications - such as reduced kidney function - while two participants experienced immunosuppression-related infections. However, they say none of the side effects led to disability or death.
Type 1 diabetes patients who undergo islet transplantation will need to take immunosuppressant drugs for the rest of their lives in order to prevent their body from rejecting the donor cells, the researchers note.
Study co-author Dr. Tom Eggerman, scientific officer for the Clinical Islet Transplantation (CIT) Consortium at the NIDDK, notes that immunosuppressant drugs can cause severe side effects.
As such, he says islet transplantation is only a sensible treatment option for people with type 1 diabetes who have severe hypoglycemia despite receiving optimal treatment, or for individuals who are already using immunosuppressant drugs after undergoing a kidney transplant.
The team will continue to monitor the study participants to determine the longer-term benefits of islet transplantation and whether these outweigh the risks associated with ongoing immunosuppressant drug use.
But for now, study co-author Dr. Nancy D. Bridges, transplantation branch chief at the National Institute of Allergy and Infectious Disease - which also helped fund the study - says their research represents the "first license-enabling trial of a cellular product for treatment of type 1 diabetes."
"Licensure is critical because it will ensure the quality, consistency and safety of the islet product; provide greater patient access to islet transplantation; and accelerate continued research that we hope would make this procedure suitable for a broader population of people with type 1 diabetes," she adds.
Earlier this month, Medical News Today reported on a study in which researchers discovered how to encourage lab-grown beta cells to mature into functioning insulin-producing cells.