Diabetes Dateline
Spring/Summer 2009

NIH Recruits Participants for Islet Transplantation Trials

The National Institutes of Health (NIH)-funded Clinical Islet Transplantation Consortium (CITC) is recruiting participants, including people with kidney transplants, for several studies aimed at improving the safety and long-term success of transplanting islets in people with type 1 diabetes.

Islets are clusters of cells in the pancreas that produce insulin—a vital hormone that moves blood glucose, also called blood sugar, out of the bloodstream and into the body’s cells. People with type 1 diabetes lose their ability to produce insulin due to an autoimmune process that destroys the islets and then must inject or infuse insulin.

Islet transplantation transfers islets from a deceased donor to a recipient’s liver. Ideally, the new islets begin making insulin and the recipient becomes insulin independent—meaning insulin injections or infusions are no longer needed. But even recipients who do not achieve insulin independence often gain better control of their diabetes and have fewer episodes of low blood sugar.

Transplanted islets, however, are recognized by the body’s immune system as foreign and are destroyed unless immunosuppressive drugs are taken to prevent rejection. These drugs can have toxic effects, including preventing islets from dividing.

Whereas 70 percent of people who receive islet transplants achieve insulin independence, only 23 percent remain insulin independent 3 years post-transplantation, according to the Collaborative Islet Transplantation Registry (CITR), which is funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The CITR is the largest collection of human islet transplantation data.

Patients who receive, on average, greater numbers of islets or multiple transplants typically have better outcomes, but donor islets are difficult to procure in adequate quantities. Better methods for islet preparation will reduce islet cell death and increase the number of islets available for transplantation.

New Studies

Eight clinical islet transplantation protocols are currently recruiting patients. The first CITC transplant took place in late 2008. CITC sites have conducted about 17 transplants thus far and have several participants waiting for donor islets to become available, according to Thomas Eggerman, M.D., director of the NIDDK’s Clinical Islet Transplantation Program.

Current CITC studies focus on

• improving the number of islets that survive transplantation
• reducing complications of the islet transplant procedure, such as bleeding and clotting of blood vessels in the liver
• reducing the side effects of immunosuppressive drugs
• achieving good blood glucose control without hypoglycemia
• following the fate of islets after transplantation and determining why donor islets sometimes fail
• evaluating new ways to safely prevent immune system rejection of donor tissues

Candidates for the studies include people with hard-to-control type 1 diabetes and people with type 1 diabetes who have had a kidney transplant.

People with hard-to-control diabetes have episodes of severe low blood glucose, called hypoglycemia, and hypoglycemia unawareness—the inability to recognize when blood glucose drops to a dangerously low level.

Kidney transplant recipients are logical candidates for islet transplantation studies, said Eggerman, because they are already taking immunosuppressive drugs, which represents the greatest risk with islet transplantation. Participants enrolled in the Islet after Kidney Transplantation study will maintain their current immunosuppressive therapy.

For more information about the islet transplantation studies, call 1–877–isletstudy (1–877–475–3878) or visit www.citisletstudy.org. The National Diabetes Information Clearinghouse (NDIC), an information service of the NIDDK, offers free publications about diabetes, including the fact sheet Pancreatic Islet Transplantation. For more information or to obtain copies, visit the NDIC at www.diabetes.niddk.nih.gov.

NIH Publication No. 09–4562
August 2009

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