Obese children's wrist size predicts heart disease

The wrist size of overweight or obese children and teens may reveal those at risk of developing cardiovascular disease.

Many studies have shown that atherosclerotic cardiovascular disease - caused by narrowing of the arteries - begins to develop in childhood. Insulin resistance, a condition in which the body makes insulin but can't use it efficiently to break down blood sugar, is a metabolic risk factor for later development of cardiovascular disease. Higher insulin levels increase the risk of developing insulin resistance, which in turn increases the risk of developing cardiovascular disease. Although excess body fat is linked to several heart disease risk factors including insulin resistance, measuring body fat in children is problematic partly because of how rapidly their bodies change during puberty.

Italian researchers sought an easy way for doctors to identify young people at greatest risk. They measured wrist circumference of 477 overweight or obese youngsters (average age 10 years) manually with a cloth tape measure and a subset of 51 of the children also underwent a painless imaging technique called nuclear magnetic resonance for precise measuring of the bony area vs. fatty area of the wrist. The study used a parameter traditionally connected to the frame size, reversing its traditional use as a correction factor for body mass index (BMI). BMI is a numeric value of weight and height used clinically to estimate whether a person is normal weight, underweight, overweight or obese.

Blood tests were also conducted on all the children to measure their insulin levels and quantify the amount of insulin resistance.

It was found that wrist circumference accounted for 12 to 17 percent of the variance in insulin resistance and in insulin levels.  The correlation between the cross-section of the wrist bones and the level of insulin in the blood or the amount of insulin resistance were much stronger than the correlation between the body mass index (BMI) and insulin levels or insulin resistance.

Several recent studies show that high blood insulin levels are associated with increased bone mass. The way in which insulin may act as a growth factor has become clearer with the discovery of insulin-like growth factor-1, a hormone with a chemical structure similar to insulin that regulates bone cell production. Wrist circumference could be a marker for increased bone metabolism in the presence of high insulin levels. If so, wrist circumference may be an easy-to-detect measure of skeletal frame size that's not severely affected by body fat variation around the time of puberty.

The above study is the first evidence that wrist circumference is highly correlated to insulin resistance. It is the wrist's bony tissue, not the fatty tissue, that explains insulin resistance, the researchers concluded. Wrist circumference is easily measured, and if this is confirmed by future studies, wrist circumference could someday be used to predict insulin resistance and cardiovascular disease risk.