Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil.
Department of Physiological Sciences, Federal University of Amazonas, Av. General Rodrigo Octavio Jordão Ramos 1200, Coroado I, Manaus, AM, 69067-005, Brazil.
Acta Diabetol. 2021 Jan;58(1):73-80. doi: 10.1007/s00592-020-01594-6. Epub 2020 Aug 28.
Conflicting results have been reported on the association of fat-free mass (FFM) and insulin resistance (IR). This study sought to test the association of FFM and IR by indexing FFM to avoid collinearity with fat mass.
This cross-sectional study comprised 11,284 volunteers, aged 38-79 years. Body composition was assessed by multi-frequency bioelectrical impedance. FFM indexed to body surface area (FFMbsa) was calculated. IR and impaired glucose tolerance (IGT) were estimated with homeostatic model assessment of insulin resistance index (HOMA-IR) and 2-h oral glucose tolerance test (2h-OGTT), respectively.
Percent body fat decreased from the 1st to the 5th quintile of FFMbsa in both women (Eta = 0.166) and men (Eta = 0.133). In women, fasting insulin (Eta = 0.002), glucose (Eta = 0.006), and HOMA-IR (Eta = 0.007) increased slightly, but 2-h plasma glucose (2-h PG) was similar across the quintiles of FFMbsa. In men, fasting insulin and HOMA-IR were similar across the quintiles of FFMbsa, whereas fasting glucose increased slightly (Eta = 0.002) and 2-h PG decreased (Eta = 0.005) toward the highest quintile of FFMbsa. The higher the odds ratio for IR, the greater the FFMbsa in both sexes. Differently, FFMbsa did not affect the odds of IGT in women, while in men the odds ratio for IGT was lower in the 5th quintile compared with the 1st quintile of FFMbsa.
Higher odds of IR associated with greater FFMbsa contrasted with lower odds of IGT associated with greater FFMbsa. IR may be misdiagnosed by HOMA-IR in adults with greater fat-free mass.
关于瘦体重（FFM）与胰岛素抵抗（IR）之间的关联，已有相互矛盾的结果报道。本研究旨在通过将 FFM 指数化以避免与脂肪量的共线性，来检验 FFM 与 IR 之间的关联。
这项横断面研究纳入了 11284 名年龄在 38-79 岁的志愿者。通过多频生物电阻抗法评估身体成分。计算了 FFM 与体表面积（FFMbsa）的比值。采用稳态模型评估的胰岛素抵抗指数（HOMA-IR）和 2 小时口服葡萄糖耐量试验（2h-OGTT）分别估计 IR 和糖耐量受损（IGT）。
在女性（Eta=0.166）和男性（Eta=0.133）中，FFMbsa 的第 1 到第 5 五分位数，体脂百分比逐渐降低。在女性中，空腹胰岛素（Eta=0.002）、血糖（Eta=0.006）和 HOMA-IR（Eta=0.007）略有增加，但 2 小时血糖（2-h PG）在 FFMbsa 的五分位之间相似。在男性中，FFMbsa 的五分位之间空腹胰岛素和 HOMA-IR 相似，而空腹血糖略有升高（Eta=0.002），2-h PG 降低（Eta=0.005），向 FFMbsa 的最高五分位。IR 的优势比越高，男女的 FFMbsa 越大。相反，FFMbsa 并不影响女性发生 IGT 的几率，而在男性中，与 FFMbsa 的第 1 五分位相比，第 5 五分位发生 IGT 的比值比更低。
与较低的 FFMbsa 相关的较低的 IGT 几率相比，与较高的 FFMbsa 相关的 IR 的优势比更高。在具有更大的无脂肪质量的成年人中，HOMA-IR 可能会错误诊断 IR。
