Alvarez Jessica A, Bush Nikki C, Hunter Gary R, Brock David W, Gower Barbara A
Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Obesity (Silver Spring). 2008 Dec;16(12):2739-44. doi: 10.1038/oby.2008.437. Epub 2008 Oct 16.
This study tested the hypotheses that correlations between direct measures of insulin sensitivity and proxy indices of insulin sensitivity derived from fasting values, (i) would not be affected by ethnicity, and (ii) would be stronger in overweight vs. weight-reduced states. We further hypothesized that associations between proxy indices and fat distribution would be similar to those between directly measured insulin sensitivity and fat distribution. Testing was performed in weight-stable conditions in 59 African-American (AA) and 62 white-American (WA) overweight, premenopausal women before and after a weight loss intervention. Subjects were retested 1 year following weight loss. Proxy indices were correlated against the insulin sensitivity index S(I) determined via minimal modeling. Fat distribution was assessed using computed tomography. Correlations between Si and proxy indices were consistently stronger among overweight women (r = 0.44-0.52) vs. weight-reduced women (r = 0.18-0.32), and among AA (r = 0.49-0.56, baseline; 0.24-0.36, weight-reduced) vs. WA (r = 0.38-0.46, baseline; 0.19-0.31, weight-reduced). Among subjects who regained >3 kg after 1 year, correlations between S(I) and proxy indices were similar to those observed at baseline, whereas correlations were weak among women who maintained their reduced body weight. S(I) and all proxy indices were similarly correlated with intra-abdominal adipose tissue (IAAT) at baseline, but not after weight loss. In conclusion, correlations between S(I) and proxy indices were affected by both ethnicity and weight status. If proxy indices are used in multiethnic populations, or in populations including both lean and overweight/obese subjects, data should be interpreted with caution.
（i）胰岛素敏感性直接测量值与源自空腹值的胰岛素敏感性替代指标之间的相关性不受种族影响；（ii）在超重状态与体重减轻状态下，二者的相关性在超重状态下更强。我们还假设替代指标与脂肪分布之间的关联将类似于直接测量的胰岛素敏感性与脂肪分布之间的关联。在59名非裔美国（AA）和62名美国白人（WA）超重的绝经前女性中，于体重稳定状态下在减肥干预前后进行了测试。在体重减轻1年后对受试者进行重新测试。将替代指标与通过最小模型确定的胰岛素敏感性指数S(I)进行相关性分析。使用计算机断层扫描评估脂肪分布。超重女性（r = 0.44 - 0.52）与体重减轻女性（r = 0.18 - 0.32）之间，以及AA女性（r = 0.49 - 0.56，基线；0.24 - 0.36，体重减轻）与WA女性（r = 0.38 - 0.46，基线；0.19 - 0.31，体重减轻）之间，Si与替代指标之间的相关性始终更强。在1年后体重回升超过3 kg的受试者中，S(I)与替代指标之间的相关性与基线时观察到的相似，而在维持体重减轻的女性中相关性较弱。在基线时，S(I)和所有替代指标与腹内脂肪组织（IAAT）的相关性相似，但减肥后则不然。总之，S(I)与替代指标之间的相关性受种族和体重状态的影响。如果在多民族人群中或包括瘦人和超重/肥胖受试者的人群中使用替代指标，则对数据的解释应谨慎。
