No easy test exists for predicting the insulin resistance of an individual. Current guidelines suggest a cut-off for heart disease of 102 centimeters (about 40 inches) in men and 88 centimeters (about 34.5) in women, but there are questions over the accuracy of these figures.

Variables Measured

Researchers in Sweden set out to assess the ability of different body measurements and biological markers to predict insulin sensitivity.

Their study involved 2,746 healthy male and female volunteers aged between 18 and 72 years who had body mass indexes (a measure of body fat based on height and weight) from 18 to 60, and waist circumferences from 65 to 150 centimeters (about 25.5 to 59 inches).

Height, weight, waist and hip circumference were measured, and a blood sample was taken to determine insulin sensitivity. Statistical modeling was used to assess the predictive power of each variable.

Strong Independent Predictor

Waist circumference was a very strong independent predictor of insulin sensitivity.

A waist circumference of less than 100 centimeters (about 39 inches) excluded insulin resistance in both sexes. It replaces body mass index, waist:hip ratio, and other measures of total body fat as a predictor of insulin resistance, say the authors.

Waist circumference is a simple tool to exclude insulin resistance and to identify those at greatest risk (therefore, those who would benefit most from lifestyle changes), the researchers conclude.