Discovery could lead to test to identify people at risk for severe type of diabetes

September 13, 1990|By New York Times News Service

Researchers have discovered that an enzyme that plays a principal role in the development of the most severe form of diabetes is the same enzyme as one found in the brain.

The finding could lead to a simple test to screen for people who are likely to develop the disease, years before their symptoms appear. A report on the finding is being published today in the British journal Nature.

Diabetes researchers had had difficulty studying the enzyme because only small amounts of it could be found in the pancreas, which does not function properly in diabetics.

But brain researchers have been able to obtain larger amounts of the enzyme. The discovery that the two are the same will be a boon to diabetes research, experts said.

The test would identify people at risk for type-1 diabetes, also called juvenile-onset diabetes because it most often begins in childhood or adolescence.

It afflicts nearly 1 million Americans, who must rely on daily injections of insulin to regulate the body's sugar metabolism.

In type-1 diabetes, beta cells in the pancreas, which produce insulin, are attacked by the immune system and are slowly destroyed.

The reason is unknown, but many scientists believe there is a trigger, perhaps a virus, that starts the process.

The symptoms of the disease, including excessive thirst, fatigue, blurred vision and high sugar levels in the urine, do not appear until about 80 percent to 90 percent of the insulin-producing cells are destroyed.

Early detection of this cellular destruction might allow for immunotherapy to prevent the disease from progressing, the researchers said.

Dr. Steinunn Baekkeskov of the University of California San Francisco School of Medicine and colleagues at Yale University and in Denmark determined that the enzyme gutamic acid decarboxylase, which is present in large quantities in the brain, is identical to the enzyme 64K, found in the pancreas.

Eight years ago Dr. Baekkeskov found that 64K stimulates the production of antibodies in the blood of many people who eventually develop diabetes.

By isolating and producing a purified form of the protein, scientists will be able to devise a simple diagnostic test for these antibodies, said Dr. Pietro De Camilli of Yale.

But researchers cautioned that there is no way as yet to prevent the disease in people who have the antibodies.

"We still need to learn how to selectively suppress that part of the immune system that kills insulin-secreting cells," Dr. De Camilli said. "But we are now much closer to that goal."

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