Diabetes: Type 1

Description

Alternative Names

Transplantation Procedures

Islet-Cell Transplantation

Major advances in islet-cell transplantation are allowing more patients to come off insulin or reduce their use of it.

Major clinical trials are now using a specific islet-cell (also called beta-cell) transplantation procedure called the Edmonton protocol, which usually involves the following steps:

• As soon as there are sufficient numbers of islets available for transplantation, the patient is given intravenous antibiotics and oral vitamins E, B6, and A.
• A machine isolates islet cells taken from donor pancreases, generally taken from cadavers. Two or three organs are usually needed in order to supply enough islet cells to have any effect on insulin production. (This is a major limitation of the procedure.)
• Once the islets have been isolated, they are injected directly in a major vein in the patient's liver.
• The islets are carried to capillaries in the liver where they produce insulin.
• Specific agents, such as tacrolimus, sirolimus, or rapamycin (Rapamume), are used to suppress the immune system. (Unlike immunosuppressant drugs used in other transplantation procedures, these agents used do not contain steroids, which destroy islet cells.) Immunosuppressants are needed for the rest of the patient's life so that the body does not reject these foreign islet cells.
• The procedure has to be performed two or more times over a period of two to three months. This generally requires multiple pancreas donors in order to achieve complete independence from insulin therapy. This is a major limitation to the procedure.

The need for two or more donor pancreases to supply sufficient islet cells is particularly troublesome, since there are not enough pancreases available to make this procedure feasible for even 1% of patients. Researchers, then, are looking for alternative sources for islet cells. In one center, for example, researchers used pig islet cells as the donor source in children and did not administer immunosuppressant agents. Half the children responded well to this approach. Another study reports that selected patients may require only one donor. Other research is focusing on using stem cells and cells from embryos to produce insulin, but any advances in these areas are years away.

Organ Transplantation

Whole pancreas transplants and double transplants of pancreases and kidneys are proving to have a good long-term success rate for selected type 1 patients. The operations help to prevent further kidney damage, and long-term studies are finding that they may even eventually reverse some existing damage. There is some evidence that heart disease and diabetic neuropathy improves after pancreas transplantation (although not retinopathy). One 10-year study reported that survival rate at 10 years was 76.3%, and two-thirds of the patients had both pancreas and kidney function. Immunosuppressive drugs are also needed life-long with this procedure. Experts are now recommending transplants in cases of end-stage kidney failure or when diabetes poses more of a threat to the patient's life than does the transplant itself.

Uncontrolled diabetes causes damage to many tissues of the body including the kidneys. Kidney damage caused by diabetes most often involves thickening and hardening of the internal kidney structures. Strict blood glucose control may delay the progression of kidney disease in type 1 and type 2 diabetics.