BAKERSFIELD, Calif. -- For around $500, consumers can have their DNA analyzed for genes that are linked to various diseases.

There are many different genes that are implicated in common illnesses such as diabetes and heart disease -- but each gene has just a small influence on a person's risk.

Researchers from Harvard wondered if adding multiple genes together could determine a person's odds of developing diabetes.

They took DNA samples from more than 6,000 patients -- some who had type 2 diabetes. Scientists analyzed patients' DNA for 10 genetic variations that have been linked to diabetes risk.

But the test did not help much in predicting type 2 diabetes.

Once doctors factored in traditional risk factors such as a person's age, weight, family history and lifestyle habits, the genetic analysis only improved the prediction by 1 percent.

Experts said that DNA tests for disease may improve within a few years. But for now, patients should save their money and concentrate on lowering their odds for diabetes by eating a healthy diet, exercising and watching their weight.