ST. LOUIS — Twice as many youngsters and teens are taking medication typically used to treat or prevent Type 2 diabetes than four years ago, according to a study released Tuesday by Express Scripts of Maryland Heights, one of the nation's largest pharmacy benefit managers.

The findings could have big implications for the nation's health system, largely because Type 2 diabetes is often accompanied by serious and expensive medical complications. The release of the study coincided with government research that found more U.S. kids are overweight, a major cause of Type 2 diabetes.

"This study is the first of its kind nationally to reveal the long-suspected national increase in prevalence of children with or at risk for diabetes," said Emily Cox, Express Scripts senior director of research and one of the study's lead authors.

She said Express Scripts did the study to find ways to better manage the cost of prescriptions and understand the reasons behind rising health care costs.

In the study, Cox and other researchers reviewed the prescription records of at least 3.7 million of its members, all Americans between the ages of 5 and 19. They found the number of prescriptions for anti-diabetic medication rose to 0.6 per 1,000 children from 0.3.

The use of these medications was most prevalent in older teens. By 2005, slightly more than 1 one out of every 1,000 15 to 19-year-olds had been prescribed medication to treat or prevent Type 2 diabetes.

Type 2 diabetes is frequently referred to as adult-onset diabetes because it was most commonly found in middle-aged adults and seniors.

"The increase in Type 2 diabetes carries enormous health care risks," said Dr. Ed Weisbart, Express Scripts chief medical officer. "Diabetes is known to shorten life expectancy by about a decade, on average."