On the Other Hand
But some scientists say universal screening is premature. The test is not 100 percent accurate and, with its "low predictive value," according to Vogt, generates many false positives. For one thing, babies with the HLA genes do not necessarily develop diabetes. The same applies to babies with autoantibodies to pancreatic cells (the second screening test). "The risk level needs to be more specific and precise," says Muir. So far, he adds, the most exact measure scientists can supply is that a child has a one in seven chance of developing Diabetes 1.
In an effort to improve the worldwide accuracy of laboratory tests, the CDC and the Immunology of Diabetes Society take part in DASP (Diabetes Autoantibody Standardization Program). The goal is to encourage laboratories to evaluate the newest technologies for specificity and sensitivity. The Boston-based company PerkinElmer Life and Analytical Sciences reports that autoantibodies can be early predictors of the disease. So tracking this measure is vital, since babies and children do not exhibit the classic symptoms of diabetes until approximately 95 percent of insulin-producing cells in the pancreas have been destroyed. As an additional benefit, the test results also can be a red flag for celiac disease, a chronic digestive disorder that often precedes Diabetes 1, according to a recent study in Pediatrics (May 2004).
Still, detractors protest that the tests heighten anxiety among parents. However, studies also show that the anxiety appears to decrease over time and varies widely with the mother's educational level, ethnic group, and marital status.
Another negative experts point out is if testing does not take place within the context of a research study with appropriate follow up, parents tend to forget their child's risk level. Less monitoring of symptoms takes place. "If parents live near a city with a diabetes research program, I recommend that high-risk children participate," says Muir. "But if I lived in a small town… I wouldn't bother testing."
Bottom line, the tests are far from foolproof, says Muir, since 85 percent of children who develop diabetes do not have a close relative with the disease. Conversely, a large percentage of high-risk children show autoantibodies, but never develop diabetes. The upside to this weak genetic link is that since fewer genes are involved, there is, according to Vogt, a better chance of finding the disease's causes.
Screening for Success
The biggest downside to universal screening is the current lack of "intervention" or prevention trials. But, as the saying goes, the times are changing. In the 1990s, prevention trials using insulin failed; however, in 2002 researchers at Columbia University successfully used a drug—a monoclonal antibody—to slow the progression of diabetes. The drug lengthened the time patients produced their own insulin, improving their overall health with minimal side effects.
Although not strictly an "intervention," TRIGR (Trial to Reduce Insulin Dependent Diabetics in the Genetically at Risk), studies high-risk infants to see if diet is an environmental trigger. International in scope, TRIGR will run to 2007. Its 40 centers in the United States, Canada, Europe, and Australia, will analyze the effects of a standard cow's milk formula on infants versus a hydrolyzed version. (For more information, call 1-888-STOP-T1D or go to www.trigrnorthamerica.org.)
Experts say that as prevention trials become available in the next five years, various health organizations such as the March of Dimes will exert pressure on state legislatures to support universal diabetes screening.
What to Do
Meanwhile, parents of high-risk newborns should follow the recommendations from the CDC:
- Stay informed about the disease and visit your pediatrician regularly.
- For the latest listing of prevention trials, access Internet websites such as the American Diabetes Association (www.diabetes.org), the Juvenile Diabetes Research Foundation (www.jdrf.org) and the National Institutes of Health (www.nih.gov).
- Contact your local diabetes chapter for support and education.
- Watch for symptoms of thirst and frequent urination in your child.
A Last Word
While the debate about diabetes screening in newborns is raging, laboratory technology is quietly and rapidly improving. Currently, 55 laboratories in 17 countries are experimenting with automated fluorescent DNA sequencing, radioimmunoassay, and remote monitoring to develop better diagnostic technologies. Laboratories not only consider accuracy but also cost-effectiveness.
"Greater efficiency of time is important, says Harry Hannon, Ph.D., head of the CDC's Newborn Screening Laboratory. "We would like to look at various conditions at the same time."