Fat distribution and insulin response in prepubertal African American and white children

Ethnic differences in obesity-related disease prevalence may relate to differences in fat distribution or metabolism. We conducted a study in 73 African Americans and white children to examine the relation between fat distribution and insulin and to determine whether ethnic differences in fat distribution or in adiposity-insulin relations contribute to differences in insulin concentrations. Fasting and postchallenge insulin concentrations were determined by oral-glocose-tolerance test, total body fat by dual-energy X-ray absorptiometry, and subcutaneous abdominal (SAAT) and intraabdominal (IAAT) adipose tissue by computerized tomography. African Americans had greater fasting insulin (X +/- SD: 79 +/- 37 compared with 55 +/- 23 pmol/L,P<0.01), incremental 30-min insulin (567 +/- 438 compared with 300 +/- 304 pmol/L,P<0.01). In multiple linear regression, fating insulin was independently related to total fat within both ethnic groups (model R-2=0.42 and 0.52 for African Americans and whites, respectively), incremental 30-min insulin to total fat and IAAT in whites only (model R-2=0.71), and AUC to SAAT in African Americans only (model R-2=0.49). Adjusting insulin indexes for adiposity did note eliminate the significant effect of ethnicity. In general, relations between adiposity and insulin were stronger in whites than in African Americans. African American children had higher insulin concentrations than white children after total body fat, IAAT, and SAAT were controlled for. However, strong relations between adiposity (total and abdominal) and insulin in both groups suggest that obesity may contribute to disease risk regardless of ethnicity.