There are already several different ways to tell if you’re at increased risk of heart disease — whether you’re overweight, or have high cholesterol or high blood pressure, for example — but researchers want to add one more potential red flag for heavy youngsters: the size of their wrist.
For young children who are overweight, researchers say that current measures for predicting their risk of heart disease aren’t that accurate. Body mass index (BMI), a ratio of height and weight, may miss potential warning signs since it doesn’t take into consideration fat distribution — namely the visceral fat that accumulates around the middle and can be particularly hazardous for the heart. Visceral fat is more likely to lead to insulin resistance, the first signs of diabetes, which also puts the heart at risk.
Meanwhile, waist-circumference measures, while effective at picking up growing risks associated with visceral fat in adults, are less useful in children, since many youngsters will gain weight around the middle before a growth spurt melts it away.
So based on evidence that insulin has a direct effect on bone growth, Dr. Raffaella Buzzetti, an endocrinologist at University Sapienza in Rome, Italy, decided to test whether wrist circumference would be a better indicator of insulin resistance, and therefore potential heart disease, in young children. Reporting in Circulation, the journal of the American Heart Association, Buzzetti and her team found that wrist circumference accounted for about 12% to 17% of the differences in insulin resistance among a group of nearly 500 overweight or obese school children. The thicker the children’s wrists, the more likely they were to show signs of insulin resistance.
Buzzetti chose the wrist because it’s an easy and objective measure of bone growth, and says that the correlation makes sense, since bone contains receptors of insulin and insulin growth factor. “Insulin and insulin growth factor are anabolic hormones that act on bones, stimulating growth,” she says. “We demonstrated that there is a much stronger correlation between insulin resistance and wrist circumference than to BMI. This could be a very good marker in the future for pediatricians to measure.”
In fact, when the researchers calculated how much of the insulin variation could be explained when they added BMI to the wrist circumference measure, there was only a 1% change, suggesting that wrist circumference accounts for most of the differences in insulin resistance.
For now, the scientists have confirmed only the link between wrist bone size and insulin resistance; they have yet to determine whether measurements of the bones hint at possible imbalances in insulin levels.
Further, the results do not suggest that every child with thick wrist bones is at risk of insulin resistance and therefore heart disease. But the findings do suggest that among youngsters who are already overweight or obese, the easy-to-take measurement may be more effective than BMI at alerting doctors to those who may be at greater risk of developing heart problems in coming years, says Buzzetti. “Bone is becoming a very interesting target to study because it can secrete hormones and receive messages from other glands, so we know it has a very active role in metabolism,” she says. Why not take advantage of that relay role to identify reversible health risks at an early age?