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Fat distribution and insulin response in prepubertal African American and white children
B A Gower1, T R Nagy, C A Trowbridge
1Department of Nutrition Sciences, University of Alabama at Birmingham, and the UAB Obesity Research Center, 35294, USA. bgower@uab.edu
Insights
African American children have higher insulin levels than white children, even after accounting for body fat. This suggests ethnicity plays a role in insulin regulation and obesity-related disease risk.
Area of Science:
- Pediatric Endocrinology
- Metabolic Health
- Ethnic Disparities in Health
Background:
- Obesity-related disease prevalence varies across ethnic groups, potentially due to differences in fat distribution and metabolism.
- Understanding these ethnic differences is crucial for targeted health interventions.
Purpose of the Study:
- To investigate the relationship between fat distribution and insulin levels in African American and white children.
- To determine if ethnic differences in fat distribution or adiposity-insulin relationships contribute to variations in insulin concentrations.
Main Methods:
- Study involved 73 African American and white children.
- Insulin concentrations measured via oral-glucose-tolerance test.
- Total body fat assessed by dual-energy X-ray absorptiometry; abdominal adipose tissue (subcutaneous and intraabdominal) quantified by computerized tomography.
Main Results:
- African American children exhibited significantly higher fasting insulin, 30-minute post-challenge insulin, and area under the insulin curve (AUC) compared to white children.
- Fasting insulin was independently related to total body fat in both groups.
- Relationships between insulin and specific fat depots (intraabdominal adipose tissue, subcutaneous abdominal adipose tissue) varied by ethnicity, with stronger associations generally observed in white children.
- Ethnic differences in insulin concentrations persisted even after adjusting for adiposity measures.
Conclusions:
- African American children present with higher insulin concentrations than white children, independent of overall adiposity and abdominal fat distribution.
- While strong associations between adiposity and insulin exist in both groups, suggesting obesity contributes to disease risk across ethnicities, ethnic-specific factors influence insulin regulation.
Abstract:
Ethnic differences in obesity-related disease prevalence may relate to differences in fat distribution or metabolism. We conducted a study in 73 African American 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-glucose-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 < 0.001), and incremental area under the insulin curve (AUC; 262 +/- 209 compared with 164 +/- 156 pmol/L, P < 0.01). In multiple linear regression, fasting insulin was independently related to total fat within both ethnic groups (model R2 = 0.42 and 0.52 for African Americans and whites, respectively), incremental 30-min insulin to total fat and IAAT in whites only (model R2 = 0.71), and AUC to SAAT in African Americans only (model R2 = 0.49). Adjusting insulin indexes for adiposity did not 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.