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Islet transplantation restores blood sugar control in type 1 diabetes

People with type 1 diabetes need to closely monitor their blood glucose levels. AndreyPopov/iStock/Thinkstock

Diabetes is a disorder in the regulation and use of glucose in the blood. Glucose is a sugar that serves as fuel for the body. When blood glucose levels rise, beta cells in the islets of the pancreas normally make and secrete the hormone insulin. Insulin triggers cells to take up sugar from the blood.

In type 1 diabetes, the body’s own immune system attacks and destroys pancreatic beta cells. People with type 1 diabetes require lifelong treatment that involves frequent (3 or more times daily) measurement of blood glucose and administration of insulin to maintain blood sugar levels. 

If blood sugar levels become very low (hypoglycemia), symptoms such as tremors and sweating typically prompt a person to eat or drink to raise their blood sugar levels. However, about 1 in 3 people with type 1 diabetes can’t tell when their blood sugar is low. This impaired awareness puts them at risk for severe hypoglycemia, which can lead to seizures, loss of consciousness, and death. 

One strategy to treat type 1 diabetes is to replace the destroyed beta cells with pancreatic islets transplanted from deceased human donors. An international team of researchers—the NIH-sponsored Clinical Islet Transplantation Consortium—set out to evaluate the effectiveness and safety of this experimental procedure. The study was designed with guidance from the U.S. Food and Drug Administration to potentially serve as the basis for future licensure for the manufacture of purified human pancreatic islet cells.

The scientists enrolled 48 people who had type 1 diabetes for more than 5 years, impaired awareness of hypoglycemia, and frequent hypoglycemic events despite expert care. The participants received at least 1 transplant of islets and were given immunosuppressive drugs to prevent their immune systems from rejecting the transplants. The research was supported by NIH’s National Institute of Allergy and Infectious Diseases (NIAID), National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and other NIH components. Results appeared online on April 18, 2016, in Diabetes Care.

During the first year after the initial transplant, 88% of participants were free of severe hypoglycemic events, had near-normal control of blood glucose levels, and had restored hypoglycemic awareness. After 2 years, 71% continued to meet these criteria for transplant success.

Adverse reactions included bleeding associated with the transplant procedure as well as infections and lowered kidney function associated with the immune-suppressing drugs. Although some of the side effects were serious, none led to death or disability.

“While still experimental, and with risks that must be weighed carefully, the promise of islet transplantation is undeniable and encouraging,” says NIDDK Director Dr. Griffin P. Rodgers. The researchers are continuing to monitor the participants to assess the benefits and risks of the transplant therapy.