The longer a person is overweight, the more likely they are to develop Type 2 diabetes, researchers say.

Obesity rates among children and teens have tripled in the last few decades. Today, one in five kids in the United States between the ages of 2 and 19 are obese.

Diabetes rates are also rising. More young children and teenagers are being diagnosed with Type 2 diabetes than ever before, said Dr. John E. Anderson, vice president of medicine and science for the American Diabetes Association.

“A disease that used to be confined to older people is creeping into high schools,” Dr. Anderson said. “This obesity epidemic we have is fueling an epidemic of diabetes in young people.”

The link between obesity and Type 2 diabetes has long been known. Now, researchers find that the amount of time spent carrying around that extra weight matters as much as the weight itself.

Researchers at the University of Michigan analyzed records of about 8,000 teens and young adults. Those with a body mass index indicating they were overweight or obese had a greater chance of developing Type 2 diabetes than those whose BMI fell within the normal range.

“If you’re born in the year 2000 and the current trends continue unchecked, you will have a one in three chance of developing Type 2 diabetes,” Anderson notes.

The study’s findings were published in the Archives of Pediatrics & Adolescent Medicine.