The number of children taking medicine for treating or preventing type 2 diabetes doubled in a four-year period, according to study of prescription records.

The study, released late Tuesday by pharmacy benefits manager Express Scripts Inc., examined prescription records of at least 3.7 million U.S. children annually from 2002-2005.

The review found the number of children taking medicine for type 2 diabetes rose in that time from 0.3 per thousand to 0.6 per thousand.

The rise was most significant among pre-adolescents, with prevalence of type 2 diabetes treatment growing 106 percent among 10- to 14-year-olds, the study said.

About 90 percent to 95 percent of diabetics have type 2 diabetes, also known as non-insulin-dependent diabetes, which is associated with older age, obesity, family history of diabetes, physical inactivity and ethnicity, according to the National Institutes of Health.

“Type 2 diabetes has long been regarded as ‘adult-onset diabetes’... but this study indicates that children with or at risk of type 2 diabetes are becoming far more common,” said Ed Weisbart, chief medical officer of Express Scripts.