Compared with children in whom neither parent had IRS, children who had at least one parent with the syndrome had statistically significantly lower mean Mlbm (12.1 vs. 13.6 mg.kg(-1).min(-1); P=0.04) and higher fasting insulin (geometric means 99 vs. 76 pmol/l; P=0.01) after adjustment for sex, race, age, and Tanner stage.