Study: Simple Test More Sensitive Than Measuring BMI
By Salynn Boyles
WebMD Health News
Reviewed By Laura J. Martin, MD
April 11, 2011 -- Measuring an overweight child's wrist size appears to be a better predictor of diabetes and heart risk than calculating body mass index, new research suggests.
Wrist size was strongly correlated with insulin resistance in overweight children in the study conducted by researchers at Italy's Sapienza University of Rome.
The findings suggest that the simple, low-tech practice of using a tape measure to record wrist size could provide clinically useful information about future risk for diabetes and heart disease, lead researcher Raffaella Buzzetti, MD, tells WebMD.
Body fat is highly predictive of insulin resistance and heart disease risk in adults, but this is not as true for children because their bodies change so rapidly around the time of puberty, Buzzetti says.
Wrist circumference has been used for many decades to calculate body frame size, but the study is the first to suggest that it may also help identify children at risk for diabetes and heart disease.
“If these results are confirmed, measuring wrist circumference may prove to be an easy-to-measure marker for cardiovascular risk,” Buzzetti says.
Wrist Size Predicts Insulin Resistance
The study included 477 overweight or obese children and teens living in Italy.
Wrist circumference was calculated using a cloth tape measure, and 51 of the children also underwent imaging tests to precisely measure wrist bone vs. wrist fat.
All of the children also had blood tests to determine their insulin levels and whether they were insulin resistant.
The analysis indicated that wrist circumference accounted for between 12% and 17% of the variance in insulin levels and insulin resistance.
In contrast, body mass index (BMI) accounted for only about 1% of the variance, Buzzetti says.
The imaging tests confirmed that bone mass and not fat was most strongly correlated with wrist size.
The study appears in the latest issue of the American Heart Association (AHA) journal Circulation.
“Wrist circumference proved to be a much more sensitive clinical marker than BMI for evaluating children for insulin resistance,” Buzzetti says.
This may be because extra insulin in the blood is associated with both bone growth and insulin resistance.
Several studies have found that insulin promotes the growth of bone through the over-expression of a bone-building protein known as insulin-like growth factor 1 (IGF-1).
Expert: Simple Test May Prove Useful
AHA spokesman and preventive cardiology specialist Vincent Bufalino, MD, calls the research intriguing and says larger studies to confirm the findings are definitely warranted.
The Elmhurst, Ill., cardiologist says other measures such as BMI, waist circumference, and skin fold testing with calipers have proven to be imprecise predictors of future diabetes and cardiovascular risk in children and teens.
“One group that this is especially true for is student athletes, especially boys,” he says. “These are often big guys with big BMI numbers but they don't have much body fat.”
Bufalino says better ways to identify at-risk children are needed. In his own studies of school-aged kids in suburban Chicago, twice as many children met the definition for obese when BMI was used to assess body type as when other measures were used.
“We certainly need more precise measures to identify children at risk,” he says. “I would like to see a much bigger trial to determine if this simple test could help us to this.”
Capizzi, M., Circulation, Journal of the American Heart Association, April 11, 2011; online edition.
Raffaella Buzzetti, MD, professor of endocrinology, Sapienza University of Rome, Italy.
Vincent Bufalino, MD, cardiologist, specialist in cardiovascular disease prevention, Elmhurst, Ill.
News release, American Heart Association.
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