Differential Effects of Abdominal Adipose Tissue Distribution on Insulin Sensitivity in Black and White South African Women

Abstract

Black South African women are more insulin resistant than BMI‐matched white women. The objective of the study was to characterize the determinants of insulin sensitivity in black and white South African women matched for BMI. A total of 57 normal‐weight (BMI 18–25 kg/m2) and obese (BMI > 30 kg/m2) black and white premenopausal South African women underwent the following measurements: body composition (dual‐energy X‐ray absorptiometry), body fat distribution (computerized tomography (CT)), insulin sensitivity (SI, frequently sampled intravenous glucose tolerance test), dietary intake (food frequency questionnaire), physical activity (Global Physical Activity Questionnaire), and socioeconomic status (SES, demographic questionnaire). Black women were less insulin sensitive (4.4 ± 0.8 vs. 9.5 ± 0.8 and 3.0 ± 0.8 vs. 6.0 ± 0.8 × 10−5/min/(pmol/l), for normal‐weight and obese women, respectively, P < 0.001), but had less visceral adipose tissue (VAT) (P = 0.051), more abdominal superficial subcutaneous adipose tissue (SAT) (P = 0.003), lower SES (P < 0.001), and higher dietary fat intake (P = 0.001) than white women matched for BMI. SI correlated with deep and superficial SAT in both black (R = −0.594, P = 0.002 and R = 0.495, P = 0.012) and white women (R = −0.554, P = 0.005 and R = −0.546, P = 0.004), but with VAT in white women only (R = −0.534, P = 0.005). In conclusion, body fat distribution is differentially associated with insulin sensitivity in black and white women. Therefore, the different abdominal fat depots may have varying metabolic consequences in women of different ethnic origins.

Once fat was fat and that was that : our changing perspectives on adipose tissue

“…80 It is also possible that subcutaneous abdominal fat may play a more prominent role in determining whole-body insulin sensitivity in African than European females, as has been observed in a previous study. 79 Previous investigators have suggested that obesity in African subjects is benign. This hypothesis was based on reports that blood pressure, glucose and lipid levels were not elevated in obese compared to lean African females.…”

“…The difference in body fat distribution between population groups is also worthy of further study, particularly as African subjects have less visceral fat than BMI-matched Europids, and yet are more insulin resistant. [77][78][79] The use of high-throughput gene-screening technology, which has yielded important information on the polygenic nature of obesity via genome-wide association studies 132 should therefore be used in African populations to determine the genetic input to adiposity and body fat distribution. It is possible that ethnic differences in insulin sensitivity and the prevalence of obesityrelated disorders are due to differences in the secretory output of adipocytes.…”

The tumor necrosis factor-α gene -238 G>A polymorphism, dietary fat intake, obesity risk and serum lipid concentrations in black and white South African women

“…1,4 Differences in these relationships may be explained, in part, by ethnic differences in the distribution of inflammatory gene polymorphisms and inflammatory gene expression, 5,6 insulin sensitivity, 6 obesity risk, dietary fat and specific fatty acid intake, and serum lipid concentrations between black and white SA women. 1,7 The functional -308 G4A polymorphism within the promoter region of the TNFA gene is in close proximity to the TNFA -238 G4A polymorphism (rs361525).…”

Ethnic-Specific Associations between Abdominal and Gluteal Fat Distribution and the Metabolic Complications of Obesity: Implications for the Use of Liposuction

“…Before participating in the study, procedures and risks were explained to the subjects, all of whom gave written informed consent to participate in the study. This study is a continuation of research from our previously published work (Goedecke, 2009). …”

“…In addition, the technique used to measure IS and the duration of follow-up varied significantly between trials. Additional factors that could influence the outcome of a trial examining the metabolic effects of LVL are the site and volume of fat removed as the metabolic activity and profile of regional fat depots varies (as demonstrated by Goedecke, 2009).…”