Waist circumference (WC) is an inexpensive marker of both insulin resistance (IR) and visceral adipose tissue (VAT). As Africa is experiencing a rapid rise in diseases related to IR such as diabetes and heart disease, identifying the WC of risk in Africans would have great clinical utility. Yet the WC which predicts IR in Africans is unknown. Further WC varies by race and gender and cannot distinguish between VAT and subcutaneous adipose tissue (SAT). Nonetheless the International Diabetes Federation states until more data is available, WC thresholds determined in whites (men 94 cm; women 80 cm) should be applied to Africans. However, data from South Africa suggests that the WC threshold which best predicts IR in black women is between 90 and 100 cm and higher in women than men. Whether this is true in Africans from other regions is unknown. Our goals were to determine in Africans (a) the WC which best predicts IR and (b) whether sex differences in VAT and SAT distribution contribute to sex differences in the WC of risk. Therefore, 360 blacks born in Africa (West 52%, Central 23%, East 25%) and living in the United States (men 68%, age 38±10y (mean±SD)) had CT scans to measure VAT and SAT. OGTT were performed to determine glucose tolerance status. IR was defined by the lowest quartile of the Matsuda Index. AUC-ROC and Youden Index were used to determine the WC which best predicted IR. Compared to women, men had lower BMI (27.2±3.9 vs. 28.6±5.4, P<0.001), higher VAT and lower SAT (both P<0.001). The optimal WC for the prediction of IR in men and women were 91 cm and 96 cm, respectively. Regression analyses with VAT and sex as independent variables and either SAT or WC as dependent variables revealed an interaction (P<0.001) between sex and VAT. So at the same VAT, both SAT and WC were higher in women than men. Overall, in Africans the WC which optimally predicts IR is 91 cm in men and 96 cm in women. Higher SAT at the same level of VAT explains why the WC which predicts IR is higher in African women than men.


J. Kabakambira: None. S.M. Briker: None. R.L. Baker: None. A.B. Courville: None. L. Mabundo: None. C. DuBose: None. S.T. Chung: None. M. Rahman: None. A.E. Sumner: None.

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