The American Diabetes Association estimates that at least one million Americans are living with type 1 diabetes . This disease is due to a deficiency of insulin. In a person without diabetes, the pancreas produces and secretes the hormones insulin and glucagon, which oppose each other to keep the level of sugar in the blood (called blood sugar or blood glucose) within a healthy range. Insulin decreases blood sugar, while glucagon increases it. In the case of type 1 diabetes, the cells in the pancreas that produce insulin—islet cells—are destroyed and therefore cannot produce or release insulin. This allows sugar to build up in the blood, which leads to the classic symptoms of diabetes— excessive thirst, hunger, and urination.

Insulin injections are central to the treatment of type 1 diabetes. One or more injections per day are necessary to compensate for what the pancreas is not producing. Self-management also includes diligent monitoring of blood sugar levels (which requires pricking the finger several times daily) and careful planning of dietary intake and physical activity.

Since the 1970s, scientists have been trying to transplant healthy islet cells into people with type 1 diabetes. In a successful transplant, the new islets will make and release insulin in response to the body’s needs, thus eliminating the need for regular injections. However, islet transplantation has yet to become a safe and reliable treatment. Previous studies have used large numbers of islet cells, which require two to four donors for one recipient. Such high numbers are not feasible for routine treatment. In addition, the patient must take anti-rejection drugs to allow his or her body to accept the foreign cells; there are side effects associated with these drugs. With these concerns in mind, researchers from the University of Minnesota gave each of eight women with type 1 diabetes an islet transplant from a single donor. Their results, published in the February 16, 2005 issue of the Journal of the American Medical Association, showed no severe or unexpected side effects, and all eight women were free from insulin injections at some point during the trial.

About the Study

Researchers from the University of Minnesota, Minneapolis recruited eight women with type 1 diabetes to take part in this study. Each woman received a transplant of islet cells isolated from an organ donor pancreas. One donor was matched to each recipient. To reduce the risk that their bodies would reject the transplanted cells, the women were also given immunosuppressive therapy. This is a drug regimen that suppresses the immune system to prevent it from attacking and destroying foreign islet cells.

Researchers wanted to see if the women would become insulin independent—meaning their bodies could maintain blood sugar within a healthy range without injected insulin. The women were also monitored for signs of adverse effects.

The Findings

The volunteers reported no serious or unexpected adverse events. In addition, all eight women achieved insulin independence at some point during the study. Five women sustained this independence for longer than one year. Among the other three, independence lasted 121, 76, and 7 days before the transplants failed and patients returned to their insulin injection routines.

How Does This Affect You?

Do these results mean that insulin injections are a thing of the past? Not quite yet. This study marks a significant step forward in islet cell transplantation research. Now that researchers have achieved insulin independence with a smaller dose of transplanted cells, they must determine the factors that allowed for this success. The authors of this study believe it may be the immunosuppressive drugs used, but more study is needed to be sure.

While the immunosuppressive drug regimen continues to be refined, it should not be overlooked that transplant recipients must take these drugs for the rest of their lives. And these drugs carry some significant side effects, such as recurrent mouth ulcers (which occurred in all women in the present study), along with increased risks of infection, certain types of cancer, kidney dysfunction, and high blood pressure and cholesterol.

Clearly there are significant risks and benefits associated with islet cell transplantation. This study’s findings help further the research, but are not significant enough in this small group of patients to alter current diabetes treatment guidelines. The authors recommend more study in larger groups of people for longer periods of time to help determine how best to minimize the risks while maximizing the benefits of this promising treatment option.