Hillman Jennifer B, Huang Bin, Pinney Susan M, Biro Frank M
Cincinnati Children's Hospital Medical Center, Division of Adolescent Medicine and University of Cincinnati College of Medicine, Cincinnati, OH, USA.
J Pediatr Adolesc Gynecol. 2013 Feb;26(1):47-50. doi: 10.1016/j.jpag.2012.09.007. Epub 2012 Nov 15.
To examine whether the known association between early pubertal breast maturation and insulin sensitivity (SI) is mediated by adiposity.
Cross-sectional analyses.
Observational study examining the roles of environment, diet, and obesity on puberty.
379 girls with a mean age, 7.03 years; 62% were white and 29% black.
Pubertal development was assessed via physical examination and adiposity by body mass index Z score (BMI Z) and waist-to-height ratio. Fasting blood samples were obtained for insulin and glucose concentrations. SI was calculated with the quantitative insulin sensitivity check index (QUICKI). Analysis of variance and Sobel's test was used to assess mediation.
Fifty-five girls were pubertal (Tanner 2 breast). Breast maturation was inversely associated with SI (P = .005) and positively associated with BMI Z (P < .001) and waist-to-height ratio (P < .001). The effect of breast maturation on SI was no longer significant (P = .41) after adjusting for the effect of BMI Z, which remained significant (P < .001). Similar results were obtained when waist-to-height ratio replaced BMI Z in the models. Mediation analyses demonstrated that 75% of the association between breast maturation and SI is mediated by adiposity.
In girls, decreased SI during early puberty is largely mediated by total and visceral adiposity.
探讨青春期乳房过早发育与胰岛素敏感性（SI）之间已知的关联是否由肥胖介导。
横断面分析。
一项观察性研究，探讨环境、饮食和肥胖在青春期中的作用。
379名女孩，平均年龄7.03岁；62%为白人，29%为黑人。
通过体格检查评估青春期发育情况，通过体重指数Z评分（BMI Z）和腰高比评估肥胖程度。采集空腹血样检测胰岛素和葡萄糖浓度。用定量胰岛素敏感性检查指数（QUICKI）计算SI。采用方差分析和索贝尔检验评估中介作用。
55名女孩处于青春期（坦纳2期乳房）。乳房发育与SI呈负相关（P = .005），与BMI Z呈正相关（P < .001），与腰高比呈正相关（P < .001）。在调整BMI Z的影响后，乳房发育对SI的影响不再显著（P = .41），而BMI Z的影响仍然显著（P < .001）。当在模型中用腰高比取代BMI Z时，得到了类似的结果。中介分析表明，乳房发育与SI之间75%的关联由肥胖介导。
在女孩中，青春期早期SI降低主要由总体脂肪和内脏脂肪介导。
