ABDOMINAL FAT DISTRIBUTION AND METABOLIC RISK-FACTORS - EFFECTS OF RACE

Previous studies have shown differences between African-American and C aucasian populations in the prevalence of obesity and obesity-related diseases such as type II diabetes. The purpose of this study was (1) t o compare the insulin sensitivity index (S-1) from the minimal model i n 37 African-American and 22 Caucasian women matched for age and obesi ty, and (2) to determine whether the relationship between intraabdomin al fat distribution and S-1 (and other health risk factors) was simila r in both races. To address the second question, intraabdominal fat di stribution was assessed by computed tomographic (CT) scans in a subset of 23 African-American and 15 Caucasian women. Despite having a simil ar body mass index ([BMI] weight in kilograms divided by height in met ers squared) and waist to hip ratio (WHR), African-American women had a mean S-1 value that was approximately 36% lower than in the Caucasia n women (3.45 +/- 0.42 v 5.40 +/- 0.55 x 10(-5) min(-1)/pmol . L, P = .007). Visceral fat area was smaller in African-American women (98.0 /- 8.5 cm(2)) than in Caucasian women (117.3 +/- 12.4 cm(2)) despite s imilar BMI and WHR. Visceral fat area was strongly correlated with WHR in the Caucasian women (r = .76, P < .001), as previously observed, b ut not in the African-American women (r = .24, NS). WHR was significan tly correlated with fasting insulin and serum cholesterol in the Cauca sian women but not in the African-Americans. Visceral fat was correlat ed with metabolic risk factors in both groups, but subcutaneous abdomi nal fat was significantly correlated with S-1 and fasting insulin only in the African-American women. These results suggest that the relatio nship between body fat distribution and health risk factors may be dif ferent in African-Americans and Caucasians. Additionally, reduced insu lin sensitivity in African-American women may in part explain the high diabetes rate in this population. Copyright (C) 1996 by W.B. Saunders Company