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WEDNESDAY, Nov. 19, 2008 (Health.com) — About 11 to 18 genes can help predict a person’s likelihood of developing type 2 diabetes, two new studies say. However, those genes don’t add much more to a patient’s diabetes-risk profile than information that’s easily available, such as body mass index, family history, and lifestyle, according to the studies in the New England Journal of Medicine.

The studies included more than 20,000 men and women who were followed for 20 to 30 years to see if they developed diabetes. In both studies, the gene variants’ predictive effect was more powerful for younger people.

However, experts say that genetic testing is probably not very useful in young adults, and probably not in children either. (The studies did not include kids.)

It’s not clear how much genetic testing of children would cost, says Richard Hellman, MD, an endocrinologist in North Kansas City, Mo., who was not involved in the new research. Plus, diabetes is a complex disorder and even testing for a dozen or so genetic variants may not be all that helpful.

“As many as 500 genotypic variants are at play in the development of type 2 diabetes; it’s usually not a single one,” he says. “Lots of factors are playing a role.”

Although more research is needed about type 2 diabetes and children, the disease is still relatively rare in kids, says John Buse, MD, director of the Diabetes Care Center at the University of North Carolina in Chapel Hill. “It would be hard to justify massive screening without a specific trial in that regard.”

Next: What the studies found