Objective: The contribution of visceral adipose tissue (VAT) to insulin resistance is well-established; however, the role of subcutaneous abdominal adipose tissue (SAT) in insulin resistance remains controversial. Sex may determine which of these two components of abdominal obesity is more strongly related to insulin resistance and its consequences. The aim of this study was to determine whether both VAT and SAT contribute to insulin resistance in African Americans and to examine the effects of sex on this relationship.
Research methods and procedures: This was a cross-sectional study of 78 nondiabetic African-American volunteers (44 men, 35 women; age 33.8 +/- 7.3 years; BMI 30.9 +/- 7.4 kg/m2). VAT and SAT volumes were measured using serial computerized tomography slices from the dome of the diaphragm to the iliac crest. The insulin sensitivity index (SI) was determined from the minimal model using data obtained from the frequently sampled intravenous glucose tolerance test.
Results: In men, both VAT and SAT were negatively correlated with SI (r for both correlations = -0.57; p < 0.01). In women, the correlation coefficient between VAT and SI was -0.50 (p < 0.01) and between SAT and SI was -0.67 (p < 0.01). In women, the correlation coefficient for SI with SAT was significantly greater than the correlation coefficient with VAT (p = 0.02).
Discussion: Both SAT and VAT are strongly correlated with insulin resistance in African Americans. For African-American women, SAT may have a greater effect than VAT on insulin resistance.