Pancreatic Islet Transplant: Revolutionary Diabetes Treatment

Originally Authored by Dr. Mersad Alimoradi - March 11, 2021

Medically Reviewed and Updated by Dr. Sony Sherpa, (MBBS) - September 12, 2025

Diabetes mellitus is a lifelong chronic condition that causes your blood sugar levels to become too high. Sugar or glucose is your body’s main source of fuel, and it comes from the food you eat. Having excess sugar in your blood can cause serious health problems.

Although diabetes mellitus has no actual cure, lifestyle changes, constant sugar level monitoring, insulin, and oral diabetic medication can go a long way. Scientists have recently started investigating a promising futuristic approach to diabetes treatment: Pancreatic Islet Transplantation. So, could this potentially be a cure for diabetes?

What Causes Diabetes Mellitus?

The cause of diabetes varies by type:

• Type 1 diabetes is an autoimmune disease, and it happens when your body’s immune system attacks and destroys your pancreatic cells. This prevents your pancreas from producing insulin, the hormone responsible for lowering your blood sugar. Type 1 diabetes occurs mainly in children and young adults, and its treatment centers around insulin injections or pumps to replace the absent hormone.

• Type 2 diabetes, the more common type, is more related to genetics and lifestyle. It occurs when your body cells become unable to properly respond to insulin, and your pancreas eventually starts failing. Type 2 diabetes can occur at any age; however, it mainly affects middle-aged or older people or those with obesity. The mainstays of type 2 diabetes treatment are lifestyle changes, diabetic medication, insulin, or a combination thereof.

What Is Pancreatic Islet Transplantation?

Pancreatic islet transplantation, also known as “islet allotransplantation”, is one of the latest treatments aiming to cure type 1 diabetes, and it has been showing some encouraging results.

What Are Islets?

Pancreatic islets are small clusters of hormone-producing cells embedded throughout the pancreas. Also known as the Islets of Langerhans, each islet contains several types of endocrine cells, most notably:

• Beta cells - Secrete insulin, which helps reduce blood sugar levels
• Alpha cells - Secrete glucagon, which raises blood glucose
• Delta cells - Release somatostatin, a hormone that regulates insulin and glucagon
• PP cells and epsilon cells - Produce pancreatic polypeptide and ghrelin, respectively

These islet cells work together to regulate blood sugar and maintain metabolic balance. The beta cells are particularly important in type 1 diabetes, where the immune system mistakenly destroys them, leading to insulin deficiency and poor blood glucose control.

How Is Pancreatic Islet Transplantation Performed?

Donor Organ Procurement

Pancreatic islet transplantation requires the removal of islets of Langerhans from the pancreas of a deceased donor.

Islet Isolation and Culture

Islets are extracted using enzymatic digestion and refined through density gradient centrifugation. In each transplantation procedure, around 400,000 islets are extracted by special enzymes.

Recipient Preparation

Prior to transplantation, the patient is stabilized with insulin and started on immunosuppressive therapy.

Islet Infusion

During implantation, you will receive a local anesthetic, and your doctor will insert a catheter (thin flexible tube) through a small cut made in your upper abdomen. With the assistance of x-ray and ultrasound imaging, the catheter is guided into your liver’s portal vein, and the islets are slowly infused there to take their place.

Another islet allotransplant method includes minimally invasive open surgery. In this method, a small incision will be made in your open abdomen, and your surgeon will directly visualize the portal vein for the catheter to be inserted without the aid of radiographic imaging.

Post-Transplant Care

After implantation, the islets will begin to produce and release insulin into your blood circulation. During the next two weeks following your procedure, new blood vessels will form and the implanted islets will have their independent blood supply and will settle in place. Patients are monitored for liver complications, glycemic control, and immunosuppression side effects.

Several islet transplantations might need to be performed so that a person with type 1 diabetes can stop being dependent on insulin injections. Pancreatic islet transplantation has the potential to reduce or even eliminate the need for insulin injections in eligible individuals with type 1 diabetes.

Who Are the Best Candidates for Pancreatic Islet Transplantation?

Not all type 1 diabetes patients are good candidates for islet cell transfer. Your doctor will only consider you for a transplant surgery procedure if the possible benefits outweigh the risks of islet allotransplant. This includes immunosuppressant side effects. You are eligible for transplant surgery if you:

• Have difficulty controlling your blood sugar levels
• Experience serious episodes of low blood sugar (hypoglycemia, usually due to insulin injections)
• Have a condition that renders you unaware of your hypoglycemic episodes
• Had or plan on having a kidney transplant surgery (meaning you are or will be taking immunosuppressants either way)
• Patients undergoing total pancreatectomy for chronic pancreatitis. Since the patient’s own islets are used, no immunosuppression is required. This can preserve insulin production and prevent post-surgical diabetes in up to 50% of cases.

Eligibility Criteria

Patients with a body mass index (BMI) below 30 and an insulin requirement of less than 1 units/kg/day are generally preferred, as higher values are associated with reduced transplant success and greater islet demand.

Exclusion Criteria

You may not be eligible if you have poorly controlled cardiovascular disease, active infections, a recent history of malignancy, substance abuse, or psychiatric illness that may interfere with adherence to post-transplant care. Pregnancy and breastfeeding are also contraindications.

Islet Transplant Alone (ITA) vs. Islet After Kidney (IAK)

Candidates may receive an islet transplant alone (ITA) if they meet eligibility criteria and do not have significant kidney disease. However, for patients who have already undergone or are planning kidney transplantation, the islet transplant is typically done afterward (IAK), leveraging existing immunosuppression to minimize additional risk.

This distinction in approach was further standardized after the landmark Edmonton Protocol, which demonstrated that glucocorticoid-free immunosuppression and infusion of sufficient islet mass could lead to sustained insulin independence. As a result, today’s selection criteria for both ITA and IAK emphasize careful metabolic profiling and adequate graft function potential.

How Islet Transplantation May Help People with Type 1 Diabetes

Islet transplantation restores the body’s ability to naturally produce insulin, which helps stabilize blood sugar levels, reduces the risk of severe hypoglycemia, and may lead to insulin independence in some patients. Even when full insulin independence isn't achieved, many experience improved glucose control and reduced long-term diabetes complications.

Can Pancreatic Islet Transplantation Successfully Treat Diabetes?

Clinical trials done by the National Institutes of Health (NIH) show that nearly nine out of ten transplant patients have hemoglobin A1c (HbA1c) below 7% one year after their procedure. This HbA1c level is usually the target goal for many diabetic patients.

Even two years after their transplant surgery, 70% of patients still maintain such low HbA1c levels with minimal episodes of low blood sugar. 

Current data also shows that more than half of the patients who undergo pancreatic islet transplantation don’t require insulin injections anymore after their procedure.

Transplant recipients also report overall improvement in their quality of life, as well as better health status after pancreatic islet transplantation. Even those still on insulin after islet transplantation still find that they’ve experienced similar improvements.

While insulin independence decreases over time, many patients retain partial graft function, which improves glucose stability and reduces hypoglycemia. Reported insulin independence rates are around 50–60% at 1 year, 20–30% at 5 years, and lower beyond that. Even those requiring insulin again benefit from better glycemic control.

What Are the Risks of Pancreatic Islet Transplantation?

Unlike a whole pancreas transplant, pancreatic islet transplantation carries fewer complications, but it’s still not risk-free. Here are some of the risks faced in islet allotransplantation:

• Bleeding, blood clot formation, and post-op pain
• The transplanted islets of Langerhans not functioning
• Graft Failure or Limited Lifespan: Most islet grafts decline in function over time, requiring reintroduction of insulin.
• IBMIR (Instant Blood-Mediated Inflammatory Reaction): A major cause of early islet loss, triggered immediately after infusion into the liver.
• Development of antibodies against the donor cells, which may limit your ability to find another pancreatic islet donor in the future

Like any transplant, anti-rejection medications (called immunosuppressants) need to be taken after the procedure. Immunosuppressants can cause some serious side effects, including but not limited to:

• Increased risk of infections and cancer
• Digestive tract upset (vomiting, nausea, diarrhea)
• High blood pressure, glucose, cholesterol, triglycerides
• Kidney damage and failure

Comparison with Whole Pancreas Transplant

Islet transplantation is less invasive than whole pancreas transplantation, with fewer surgical risks and faster recovery. However, whole pancreas transplants may have higher long-term insulin independence rates. Islet transplants are preferable in patients who are poor surgical candidates or already have kidney transplants.

How Common Is Islet Transplantation & Where Is It Accepted?

Pancreatic islet transplantation is a rare procedure globally, primarily performed in specialized centers. Countries such as Canada, Australia, the United Kingdom, France, Switzerland, and Italy have established programs where islet transplantation is reimbursed and integrated into standard care for type 1 diabetes patients.

In contrast, the United States faces significant regulatory challenges. The FDA classifies islet cells as biologic drugs, requiring extensive clinical trials and premarket approval before they can be used in patients. This stringent regulation has led to a sharp decline in procedures, from 111 in 2012 to just 10 in 2021, making the U.S. a global outlier in islet transplantation.

Other Conditions Treated With Islet Autotransplantation

Islet cell transplantation, particularly islet autotransplantation (IAT), is used to treat conditions beyond type 1 diabetes. IAT is primarily utilized to manage pancreatogenic diabetes, a form of diabetes that arises after the surgical removal of the pancreas. Patients with chronic pancreatitis or frequent episodes of acute pancreatitis tend to benefit the most from this procedure.

Chronic Pancreatitis (CP)

Patients with severe and persistent pain from chronic pancreatitis may undergo total pancreatectomy. Islet cells are extracted from the removed pancreas and transplanted into the liver, where they help preserve insulin production and lower the risk of diabetes.

Recurrent Acute Pancreatitis (RAP)

Individuals experiencing repeated episodes of acute pancreatitis that significantly impact their quality of life may also be candidates for total pancreatectomy and subsequent islet autotransplantation.

Genetic or Familial Pancreatitis

In cases where pancreatitis is hereditary, leading to an increased risk of pancreatic cancer, total pancreatectomy with islet autotransplantation can eliminate the risk of cancer and help manage diabetes.

Benign Pancreatic Diseases

Islet autotransplantation has been explored for other benign pancreatic conditions requiring significant pancreatic tissue removal, such as certain benign pancreatic lesions or trauma.

Implantation Strategies

Implantation strategies refer to the methods and technologies used to place and support islets at the chosen site. These can include:

• Direct Infusion: Simple injection or infusion of islets into the selected site (e.g., into the portal vein or muscle).
• Scaffold-Based Delivery: Using biodegradable scaffolds or matrices to provide structural support, improve vascularization, and protect islets.
• Encapsulation: Encasing islets in semi-permeable biomaterials that allow nutrient and insulin exchange but shield from immune attack.
• Pre-vascularization Approaches: Preparing the implantation site with pro-angiogenic factors or stem cells before introducing islets to enhance survival and integration.
• Device-Based Delivery: Using implantable devices (macro- or micro-scale) that house islets in controlled environments, often with retrievability for safety.

Advancements and Future Outlook of Pancreatic Islet Transplantation

Pancreatic islet cell transfer is an emerging and promising treatment for individuals with type 1 diabetes, especially those who suffer from severe hypoglycemia or impaired awareness. While the therapy offers substantial benefits, including improved glucose regulation and potential insulin independence, it remains suitable for only a limited number of patients due to key barriers such as donor scarcity, graft longevity, and immunosuppression challenges.

Recent Advancements

Significant progress has been made in several areas to overcome these limitations:

• Donislecel (Lantidra): In 2023, the FDA approved Donislecel (marketed as Lantidra), the first allogeneic islet cell therapy for adults with type 1 diabetes experiencing repeated severe hypoglycemia. Some patients treated with Lantidra have remained insulin-independent for months to years post-transplant.
• Tegoprubart Immunotherapy: This novel immunosuppressive agent has shown potential to enhance graft survival while reducing the adverse effects commonly associated with standard agents, such as tacrolimus.
• Improved Islet Isolation Techniques: Innovations in enzymatic digestion, purification, and culture methods are enhancing the yield, quality, and viability of harvested islet cells.
• Novel Immunosuppressive Regimens: Advances include the use of T-cell depleting agents for induction and maintenance therapies to balance immune protection with fewer toxicities.
• Encapsulation and Bioengineering: Encapsulation methods aim to shield transplanted islets from the immune system, reducing reliance on lifelong immunosuppression.
• Stem Cell-Derived Islets: Induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) are being studied as renewable sources for generating insulin-producing islets, addressing the shortage of donor cells.

Future Directions and Research

Ongoing studies are broadening the applications of islet transplantation and enhancing clinical outcomes:

• Transdifferentiation: Efforts are underway to convert non-beta cells, such as alpha or ductal cells, into insulin-producing beta cells within the pancreas, offering a novel way to regenerate endogenous insulin function.
• Role of Alpha Cells: A deeper understanding of alpha cells and their role in glucagon regulation and glucose homeostasis may inform future islet designs that better mimic native pancreatic function.
• Expanded Indications: Although primarily used for type 1 diabetes, early studies suggest that islet transplantation may also benefit select individuals with advanced type 2 diabetes, especially when beta cell exhaustion is present.
• Alternative Cell Sources: In addition to stem cells, researchers are exploring options such as xenotransplantation from pigs, living donor islets, and optimizing islet yield from single deceased donors. Currently, cadaveric pancreata from deceased donors are the primary source of islets for transplantation. However, the limited supply of donor organs and the need for multiple pancreata per recipient present major barriers to widespread adoption, underscoring the importance of alternative cell sources and bioengineering strategies in the future.
• Alternative Transplant Sites: Researchers are investigating alternative anatomical sites for islet transplantation beyond the liver. These include the omentum, which provides a vascularized and easily accessible bed; the intramuscular space, which allows for localized engraftment and monitoring; and the subcutaneous tissue, which, though less vascular, is minimally invasive and patient-friendly. Other explored sites include the bone marrow and the kidney capsule in experimental settings. These alternatives aim to improve long-term islet survival, reduce complications linked with liver infusion, and enable better monitoring of graft function.

Ultimately, to shift pancreatic islet transplantation from an experimental therapy to a mainstream option, improvements are still needed in immunosuppressive protocols, cell sourcing, engraftment strategies, and long-term graft viability. Continued breakthroughs in biotechnology and cellular medicine are steadily moving the field toward safer, more effective, and more widely accessible treatments.

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