August 12, 2010
Dear Mayo Clinic:
Can a pancreas transplant cure diabetes?
Not necessarily. In certain people with diabetes, a pancreas transplant can restore the body's ability to secrete insulin — thus reducing blood sugar levels and eliminating the need for insulin therapy. But transplant should not be taken lightly. A pancreas transplant poses health risks and doesn't always remove the need for additional diabetes treatment.
Insulin is a hormone. When you eat, the pancreas — a gland located just behind and below the stomach — releases insulin into your bloodstream. As insulin circulates through the blood, it allows sugar to enter the cells, lowering the amount of sugar in the bloodstream. If the body doesn't have enough insulin, sugar can build up in the blood. Diabetes is the condition of having too much blood sugar (glucose).
There are two types of diabetes. Type 1 diabetes develops when the pancreas produces little or no insulin. The exact cause of type 1 diabetes isn't clear. In most people with type 1 diabetes, the body's immune system mistakenly destroys the insulin-producing (islet) cells in the pancreas. Type 2 diabetes develops when the body becomes resistant to insulin, and the pancreas is unable to make enough insulin to overcome that resistance. Exactly why type 2 occurs is unknown, although excess weight and inactivity seem to play significant roles in its development.
A pancreas transplant can be a useful treatment for some people who have diabetes. Those with type 1 diabetes are much more likely to benefit from a pancreas transplant than are those with type 2. Most pancreas transplants are performed on people who have type 1 diabetes, because a damaged pancreas is usually the main cause of high blood sugar in type 1 diabetes. In contrast, people with type 2 diabetes often have other factors — beyond the pancreas's inability to produce adequate amounts of insulin — that contribute to high blood sugar levels. So, a transplant is more likely to result in sufficient insulin production in people with type 1 diabetes than in those with type 2.
A pancreas transplant, however, has considerable risk. Serious complications can result, such as blood clots, bleeding, infection and failure of the donated organ. In addition, those who undergo a pancreas transplant must take anti-rejection medications for the rest of their lives. These medications help prevent the body's immune system from attacking and rejecting the donated pancreas. Anti-rejection medications can also cause significant side effects, including bone thinning, high cholesterol and high blood pressure.
The possible complications of transplant surgery and the medication side effects can often be more serious than the diabetes. So, a pancreas transplant is typically reserved for people whose diabetes cannot be controlled with standard treatment or those who frequently experience adverse reactions to insulin therapy.
Even when candidates for a pancreas transplant are chosen carefully, the procedure doesn't always have the intended effect. Not everyone with diabetes who has a pancreas transplant will have normal blood sugars or be able to completely stop insulin therapy. Although it can be an effective treatment option for some people with diabetes, a pancreas transplant is not necessarily a cure.
— Adrian Vella, M.D., Endocrinology, Mayo Clinic, Rochester, Minn.