The goal of gene therapy research is to prevent, treat, relieve the symptoms of or cure diseases such as diabetes. The potential benefits are great. Gene therapy in the future may be able to control the production of insulin, thus freeing patients from the need for injections, pumps and other methods of insulin administration. It might also be used to treat complications ranging from foot ulcers to kidney disease.

However, there are also certain risks associated with gene therapy. One of the major risks is the potential for infection or an immune system reaction. Vectors, the means of delivering gene therapy to a cell, have traditionally used viruses that were rendered harmless. In a few cases, however, viral vectors have been involved in causing disease or sparking a reaction in people during trials of gene therapy, sometimes fatally.

Scientists have reported progress with gutless viral vectors, which have been tested for safety on animals after the removal of harmful genes. They are also experimenting with nonviral vectors such as proteins.

Another risk involved with gene therapy for diabetes patients is hypoglycemia, low levels of glucose (blood sugar). Researchers who use gene therapy to produce insulin, particularly outside the pancreas, must avoid creating too much insulin. Excess insulin (hyperinsulinemia) leads to hypoglycemia, which can result in unconsciousness, coma and even death. Research scientists are trying to resolve this factor by adding genetic material that helps to regulate glucose levels.

Many gene therapy treatments rely on immune suppression for success. People with type 1 diabetes have an autoimmune disorder that makes the immune system destroy the insulin-producing beta cells. A primary focus of research is correcting the function of the immune system to protect the cells produced by gene therapy. However, scientists need to create a balance between reducing unwanted immune function and hindering the normal disease-fighting function of the immune system.

Human trials on gene therapy are under way for conditions including diabetic neuropathy. The U.S. National Institutes of Health has current information on trials seeking volunteers (www.clinicaltrials.gov). Patients who are interested in participating are advised to consult their physician about the potential risks and benefits.