To establish the biochemical characteristics of nonobese, overweight, and obese children as well as to determine the risk factors associated with insulin resistance in nonobese children and with non-insulin resistance in obese children in the age strata of 6 to 11 years.A total of 3512 healthy children were enrolled in a cross-sectional study. In the absence of obesity, fasting hyperinsulinemia and hypertriglyceridemia defined nonobese, insulin-resistant (NO-IR) children. In the absence of metabolic abnormalities of fasting insulin and triglycerides levels, obese children were defined as obese, not insulin-resistant (O-NIR) children.The gender- and age-adjusted prevalence of NO-IR and O-NIR was 6.6% and 21.3%, respectively. In the age-, gender-, and birth weight-adjusted analysis, family history of hypertension (FHH) in both maternal and paternal branches (odds ratio [OR]: 1.514; 95% confidence interval [CI]: 1.2-3.9; P = .04) was associated with NO-IR children. In the analysis adjusted by gender, age, waist circumference (WC), BMI, FHH, and family history of diabetes, high birth weight was associated with NO-IR children (OR: 1.319; 95% CI: 1.2-2.1; P = .04). Finally, in the gender-, age-, family history-, and birth weight-adjusted analysis, a WC lower than the 95th percentile was associated with a lower odds of insulin resistance among obese children (OR: 0.96; 95% CI: 0.91-0.98; P < .0005).FHH and high birth weight are associated with NO-IR children, and a low WC is associated with lower odds of O-IR children.