The number of U.S. children taking medications for chronic diseases is growing, with some interesting gender differences.

Researchers had already established that chronic conditions are on the rise among the not-yet-adult set, but how those conditions are being treated ... that has been less well understood. Now we have a clearer picture.

Using prescription claim data for 2002 to 2005, researchers at Express Scripts, St. Louis University and Kansas Health Institute evaluated the use of drugs to treat hypertension, high cholesterol, Type 2 diabetes, depression, ADD/ADHD and asthma in insured children ages 5 to 19.

The use of all medications rose, but the use of drugs to treat Type 2 diabetes soared. The rate of growth for drugs to treat these conditions:

Hypertension: 1.8%

High cholesterol: 15%

Diabetes: 103.3%

Depression: 1.8%

ADD/ADHD: 40.4%

Asthma: 46.5%

The researchers spent some time theorizing about the reason teenage girls had such a greater use of diabetes drugs than did boys -- 146.6% growth compared with 38.7%. Obesity is a primary contributor to diabetes, and yet obesity rates didn't account for the discrepancy. As the researchers pointed out, boys have had higher rates of the condition in recent years, as well as higher growth in those rates.

Possible reasons, they said, included the use of the diabetes drug metformin to treat polycystic ovary syndrome and metabolic syndrome, as well as the higher rate of doctor visits by teenage girls compared with teenage boys.

But then girls also had higher growth in the use of antidepressants and medications for ADD/ADHD.

Referring to the overall findings, lead author Emily R. Cox said in a news release: