Diabetes is a leading cause of blindness, end-stage kidney failure, and leg amputations, and it also increases the risk for heart disease. Considered incurable, diabetes mellitus causes high blood sugar levels due to the body's inability to produce or effectively use insulin, a hormone secreted by the pancreas that aids in storing or converting glucose from food into energy. People with type 2 diabetes either do not produce enough insulin or their bodies have difficulty putting the available insulin to work; some people with type 2 diabetes require insulin injections. People with type 1 diabetes produce little or no insulin and require multiple daily injections of insulin. The main treatment regimen for type 1 diabetes is insulin injections throughout the day, measuring blood sugar levels, watching one's diet, and planning structured meals and activities.

Doctors have attempted to transplant insulin-producing islet cells from donated pancreases into patients with severe, unstable diabetes. The results were that these recipients were able to maintain normal blood sugar levels without taking insulin shots. So can islet-cell transplants mean the end of daily insulin injections for people with diabetes?

One type of islet-cell transplan method follows a procedure called the Edmonton protocol. This includes transplanting cells immediately after removal from the donated pancreas, removing foreign proteins from the cells, and adding islets from a second pancreas if blood sugars start to rise. Doctors infuse the cells into the patient's liver during a simple procedure, and the process carries less risk than an organ transplant.

Several small studies have looked at islet-cell transplantation in those with type 1 diabetes. The studies overall showed mixed support for transplantation. A study of 36 patients that used the Edmonton protocol found that transplantation did restore insulin production in the body, as well as keep blood sugar levels stable. However, the transplant did not make it able for most patients to be free from their insulin regimen over time. But another small study using the Edmonton protocol was able to report its patients as achieving insulin independence. Overall, the transplanted cells allow patients to avoid life-threatening blood-sugar crashes, although after several years, some people may still end up taking insulin.

Doctors also note that islet-cell transplant is not the end of treatment. After surgery, a patient takes antirejection medications so that her body does not reject the new pancreas. There are side effects to antirejection medications that include suppression of the immune system and an increased risk of cancer and infections.

Lack of donated pancreases will limit the number of people who can receive islet-cell transplants. With limited available organs, scientists are still searching for new sources of islet cells. Some researchers are cultivating human islet cells in the laboratory, while others are developing cell lines that produce insulin. Until these or other new methods prove to be expedient, safe and effective, transplants will rely on donated organs.