Diabetes Blood Test Pinpoints Children at Risk : Medicine: Discovery of telltale antibodies opens the way to preventive therapy to halt or slow the disease in afflicted youngsters.

WASHINGTON — Eric McComas, 6, of Silver Spring, Md., was a toddler when he was diagnosed with juvenile diabetes and started daily injections of insulin to save his life. Last year, his younger brother Sean, barely out of diapers, also developed diabetes. Now his parents are worried about their third and eldest son, Chris.

So they took him to Children’s Hospital here for a new type of blood testing that could predict whether he too might get diabetes in the next several years. “It was almost a panic reaction,” said his mother, Pat McComas.

The test showed that Chris, 8, does have the telltale antibodies that mean he might get diabetes, but other tests showed that for the moment he is fine. Years ago, that would be the end of the story--the McComas family would be left with the sword of Damocles over their eldest child.

But today the family has other options. Here and abroad, researchers are experimenting with a variety of ways to delay or prevent diabetes in high-risk children like Chris.

In one study at Children’s Hospital, for example, these children are getting high doses of a vitamin preparation in hopes of blocking the development of the disease. McComas is ready to enroll her son, should he become officially pre-diabetic: “If we can prevent diabetes by taking a vitamin, we’d be crazy not to do it.”

Preventive strategies range from trying a vitamin treatment to using a potent drug that suppresses the immune system to giving insulin orally or by injection, as if the child were already diabetic. Clinical trials to test these strategies have begun at several sites in the United States, including Children’s Hospital in Washington, in New Zealand and in Europe.

In the past, parents might have thought, “Why bother to get your children tested if there’s nothing you can do about it,” said H. Peter Chase, director of the Barbara Davis Center for Childhood Diabetes in Denver, which is collaborating on studies with Children’s Hospital and the Joslin Diabetes Center in Boston. “Now that we’ve got studies in progress, it’s very important for families to participate so we can find out once and for all if this is protective.”

The offspring, siblings and young parents of people with juvenile-onset diabetes (also called Type I diabetes) have a much greater chance of developing the disease than the general population--one in 15 will eventually lose the insulin-producing function of the pancreas, which causes diabetes. The risk is one in 200 for most people.

Without insulin, the body cannot regulate its metabolic rate. Daily injections of insulin prevent shock, coma and death.

Diabetes is, at least in part, an autoimmune disease in which the body for some unknown reason begins to attack and destroy the islet cells of the pancreas, which secrete insulin.

People appear to inherit a predisposition to juvenile diabetes, but an environmental agent, such as a virus, may trigger it. Type I diabetes usually occurs before age 40.

As long as 20 years ago, a blood test was devised that could detect antibodies targeting the pancreas before the actual onset of diabetes. But the tests were not completely reliable, and there was nothing to be done to change a child’s fate.

In the last two years, however, these antibody blood tests have been refined so that they can predict which children have a 95% likelihood of developing juvenile diabetes over the next three or four years.

An antibody test is used to screen for children at high risk, and then an intravenous glucose tolerance test is given that can show whether the child’s metabolism of sugar is already slightly impaired.

At Children’s, siblings ages 4 to 18 identified as pre-diabetic by the blood test and the glucose-tolerance test will be given high doses of an oral vitamin preparation that has been found to prevent the disease in diabetes-prone mice.

At Boston’s Joslin Diabetes Center, researchers are giving low-dose insulin injections to pre-diabetic children to study if it works as a preventive measure. The concept is that by giving extra insulin, the islet cells of the still healthy pancreas need to produce less--leaving them more metabolic energy to fight off an immune system attack and prevent the disease from taking hold.

Susan Fuge of Chevy Chase, Md., had her two younger children tested recently at Children’s and now awaits the results. Her eldest, Jeffrey, 10, was diagnosed as having juvenile diabetes at age 2, when he went into a coma.

Even without a proven preventive therapy, Fuge said, the new testing is a way to identify diabetes before the traumatic symptoms that usually prompt a diagnosis.

“Every time my other children have had the flu, if it took more than 24 hours to get over it, I thought, ‘Oh my God, I’ve got another diabetic,’ ” Fuge said. “I really did not want to find out that either of them was pre-diabetic unless there was something they could do about it. I thought there was no point.”

Now she is interested in both the programs at Children’s and at Joslin, should results come back positive for Ali, 7, or Tommy, 4.