Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Diabetes. 2014 Mar;63(3):1093-102. doi: 10.2337/db13-1483. Epub 2013 Dec 18.
We previously showed that ethnicity modifies the association between adiposity and insulin resistance. We sought to determine whether differential body fat partitioning or abnormalities in muscle insulin signaling associated with higher levels of adiposity might underlie this observation. We measured the insulin sensitivity index (ISI), percentage of body fat (%body fat), visceral (VAT) and subcutaneous (SAT) adipose tissue, liver fat, and intramyocellular lipids (IMCL) in 101 Chinese, 82 Malays, and 81 South Asians, as well as phosphorylated (p)-Akt levels in cultured myoblasts from Chinese and South Asians. Lean Chinese and Malays had higher ISI than South Asians. Although the ISI was lower in all ethnic groups when %body fat was higher, this association was stronger in Chinese and Malays, such that no ethnic differences were observed in overweight individuals. These ethnic differences were observed even when %body fat was replaced with fat in other depots. Myoblasts obtained from lean South Asians had lower p-Akt levels than those from lean Chinese. Higher adiposity was associated with lower p-Akt levels in Chinese but not in South Asians, and no ethnic differences were observed in overweight individuals. With higher %body fat, Chinese exhibited smaller increases in deep SAT and IMCL compared with Malays and South Asians, which did not explain the ethnic differences observed. Our study suggests that body fat partitioning does not explain interethnic differences in insulin sensitivity among Asian ethnic groups. Although higher adiposity had greater effect on skeletal muscle insulin sensitivity among Chinese, obesity-independent pathways may be more relevant in South Asians.
我们之前的研究表明，种族会影响肥胖与胰岛素抵抗之间的关联。我们试图确定，是否与更高水平的肥胖相关的不同身体脂肪分布或肌肉胰岛素信号异常可能是造成这一观察结果的原因。我们在 101 名中国人、82 名马来人和 81 名南亚人中测量了胰岛素敏感性指数（ISI）、体脂肪百分比（%body fat）、内脏（VAT）和皮下（SAT）脂肪组织、肝脏脂肪和肌内甘油三酯（IMCL），以及中国人和南亚人的培养肌母细胞中磷酸化（p）-Akt 水平。瘦的中国人和马来人的 ISI 高于南亚人。尽管在所有种族群体中，当 %body fat 较高时，ISI 较低，但这种关联在中国人和马来人中更强，以至于超重个体中没有观察到种族差异。即使在使用其他部位的脂肪替代 %body fat 时，也观察到了这些种族差异。从瘦的南亚人获得的肌母细胞中 p-Akt 水平低于从瘦的中国人获得的肌母细胞。较高的肥胖与中国人的 p-Akt 水平降低有关，但在南亚人中没有观察到这种关联，并且在超重个体中没有观察到种族差异。随着 %body fat 的增加，中国人与马来人和南亚人相比，深部 SAT 和 IMCL 的增加幅度较小，但这并不能解释所观察到的种族差异。我们的研究表明，身体脂肪分布并不能解释亚洲种族群体之间胰岛素敏感性的种族差异。虽然中国人的更高肥胖对骨骼肌胰岛素敏感性的影响更大，但在南亚人中，与肥胖无关的途径可能更为重要。
