OBJECTIVE—The objective of this study was to compare insulin resistance relative to body fat and the associated compensatory responses in 57 healthy children living in Los Angeles, California (14 Caucasians, 15 African-Americans, and 28 Hispanics).

RESEARCH DESIGN AND METHODS—Insulin sensitivity and acute insulin response were determined by intravenous glucose tolerance test. Insulin secretion, hepatic insulin extraction, and insulin clearance were estimated by C-peptide and insulin modeling.

RESULTS—Insulin sensitivity was significantly lower in Hispanics and African-Americans compared with Caucasian children, and acute insulin response was significantly higher in African-American children. No ethnic differences were noted in the first-phase secretion, but second-phase insulin secretion was significantly higher in Hispanic children than in African-American children (200 ± 53 vs. 289 ± 41 nmol/min; P = 0.03). The greater acute insulin response in African-Americans, despite lower secretion, was explained by a lower hepatic insulin extraction in African-Americans compared with Hispanics (36.6 ± 2.9 vs. 47.3 ± 2.2%; P = 0.0006).

CONCLUSIONS—In conclusion, Hispanic and African-American children are more insulin resistant than Caucasian children, but the associated compensatory responses are different across ethnic groups.