Abstract 13224: Variation in the Waist Circumference of Risk in Black Populations: A Comparison of African Immigrants to African Americans
Whether the waist circumference (WC) of risk differs among populations of African descent is unknown. Defining the “WC of risk” as the WC which best predicts insulin resistance, WC of risk was compared in African American and African immigrant men. The participants were 198 men (62% African immigrants) who self-identified as healthy. All of the African immigrants were born in countries from equatorial Africa (West (51%), Central (29%) and East (20%)). Using the minimal model, insulin resistance was defined by the lowest quartile of the insulin sensitivity index (SI<2.29). Receiver operating characteristic (ROC) curves and the Youden Index were used to identify the optimal WC. Glucose tolerance status was determined by OGTT. Measurement of visceral (VAT) and subcutaneous adipose tissue (SAT) was obtained at L2-3 by computerized tomographic (CT) scan. Compared to African Americans, Africans were older (37±8 vs. 34±8y, P=0.05, mean±SD) and had a lower BMI (27.3±3.8 vs. 29.3±5.5 kg/m2, P<0.01). Adjusting for age and BMI, WC did not differ by ethnicity (93±5 vs. 94±6 cm, P=0.12), but Africans had higher VAT (P<0.01) and lower SAT (P<0.01). The WC which best predicted insulin resistance in Africans was 92 cm (AUC-ROC: 0.77±0.06 (SE)) and in African Americans was 102 cm (AUC-ROC: 0.76±0.07). The WC of risk in Africans by African region of origin was 92 cm for West Africans, 91 cm for Central Africans and 97 cm for East Africans. At every level of WC, VAT was higher in Africans than AA. In addition, the OGTT revealed that Africans were more likely than African Americans to have glucose intolerance (35% vs. 22%, P<0.01) or previously undiagnosed diabetes (7% vs. 0%, P<0.01). Overall, the WC of risk is ~10 cm lower in Africans than African Americans, and can be explained by higher VAT. The lower WC of risk in Africans is concordant with their higher rate of abnormal glucose tolerance at a lower BMI.
- © 2013 by American Heart Association, Inc.