Islet cells (islets of Langerhans) are clusters of cells inside the pancreas that produce insulin, the hormone required to move glucose (sugar) into cells for energy. The pancreas, an organ about the size of a hand, is located behind the lower part of the stomach.
Diabetes develops when the body doesn’t make enough insulin, cannot use insulin properly, or both, causing glucose to build up dangerously in the blood. Type 1 (juvenile onset) diabetes is an autoimmune disorder in which the body mistakenly attacks and destroys the islet cells of the pancreas. Children and young adults diagnosed with type 1 diabetes must carefully control their diet and take insulin daily to live. Type 2 (adult onset) diabetes usually begins with insulin resistance, a condition in which the body has difficulty using insulin effectively. Over time, insulin production declines and eventually many people with type 2 diabetes will also need to take insulin.
Islet transplantation, the transplanting of healthy islet cells from an organ donor, may make it possible to replace insulin production and help people diagnosed with type 1 diabetes live without daily insulin injections.
The Collaborative Islet Transplant Registry, funded by the National Institute of Diabetes and Digestive and Kidney Diseases, presented data in its 2006 Annual Report from 23 islet transplant programs on 225 patients who received islet transplants between 1999 and 2005. According to the report, nearly two-thirds of recipients achieved “insulin independence” for at least a 2-week period during the first year after transplant, but insulin independence was difficult to maintain over time. Six months after their last infusion of islets, more than half of recipients were free of the need for insulin injections, but at 2-year follow-up, the proportion dropped to about one-third of recipients. The report described other benefits of islet transplantation, including reduced need for insulin among recipients who still needed insulin, improved blood glucose control, and greatly reduced risk of episodes of severe hypoglycemia.