By Serena Gordon
MONDAY, May 21 (HealthDay News) -- Many American teenagers, including some with a normal, healthy weight, already have one or more risk factors for heart disease, researchers say.
About 22 percent of today's teens have borderline-high or already high LDL cholesterol -- that's the bad type. And 15 percent have pre-diabetes or diabetes, according to the new research based on data spanning from 1999 to 2008.
When the study authors looked at the year-by-year differences, however, one risk factor stood out. At the start of the study period, the rate of pre-diabetes/diabetes was 9 percent. By the end of the study, that number was 23 percent.
"Pre-diabetes and diabetes increased over time among adolescents," said the study's lead author, Ashleigh May, an epidemiologist at the U.S. Centers for Disease Control and Prevention.
May added that the rate of pre-diabetes/diabetes as well as the other cardiovascular risk factors went up as weight increased.
The study was released online May 21, and will be published in the June print issue of Pediatrics.
Cardiovascular disease is the leading cause of death in U.S. adults, according to background information in the study. Although most manifestations, such as stroke and heart attack, don't occur until adulthood, there's been increasing evidence that risk factors for cardiovascular disease may be evident much sooner. And, with more and more American children and teens becoming overweight and obese, health experts are increasingly concerned about the possibility of cardiovascular risk factors showing up at younger ages.
The current study reviews data from the U.S. National Health and Nutrition Examination Survey from 1999 through 2008. The survey includes a nationally representative sample of the U.S. population. For this study, the investigators focused on the 3,383 teens who were between 12 and 19 years old.
During the study period, 14 percent either had or were at risk for high blood pressure (prehypertensive/hypertensive), 22 percent had borderline-high or high bad (LDL) cholesterol levels, and 6 percent had low levels of the good (HDL) cholesterol.
For the study period overall, 15 percent of teens were classified as having pre-diabetes or diabetes. The rate of pre-diabetes/diabetes was the only risk factor that increased from the beginning of the study to the end.
May noted that this might have more to do with how they tested for diabetes, as they only measured one fasting blood sugar level. Normally, diabetes or pre-diabetes isn't diagnosed unless there are at least two abnormal fasting blood sugar levels, because levels tend to fluctuate.
In addition, May said the plateauing of the other risk factors appears to mirror the plateau that has occurred in childhood obesity. But, she added, both the diabetes trend and the plateauing trend will need more research over time to see if these trends continue.
The study also found that as weight increased, so did the cardiovascular risk factors. However, a significant number of normal-weight children also showed signs of trouble. About 10 percent were in the pre-hypertensive/hypertensive category, more than 15 percent had elevated bad cholesterol and more than 10 percent had pre-diabetes/diabetes, the results showed.
Dr. Dorothy Becker, chief of endocrinology and diabetes at Children's Hospital of Pittsburgh, said she wasn't surprised by the findings, even that some normal-weight children were showing heart disease risk factors. She said that anyone who's eating a diet high in sugar and fat will likely have problems, even if it isn't readily apparent in their weight.
"It's not just what you look like. You can have a pretty lousy lifestyle without being overweight," she said.
Doctors, parents, school and hospital administrators, and community leaders all need to take overweight and obesity seriously, she said. "Physicians need to say this is important. It's as big a risk to your health as smoking or unprotected sex," Becker said.