静脉葡萄糖耐量试验中血清瘦素和游离脂肪酸的动态变化

Dynamic of serum leptin and free fatty acid levels during intravenous glucose tolerance test

目的 不同胰岛素抵抗和胰岛 β细胞功能者通过测定静脉葡萄糖耐量试验 (IVGTT)中的血糖、胰岛素、瘦素和游离脂肪酸 (FFA)的血清水平来探讨影响瘦素和FFA分泌的因素。方法 以口服葡萄糖耐量试验确定正常对照组 ( 7例 ) ,超重 /肥胖组 ( 10例 ) ,糖耐量受损组 ( 12例 )和 2型糖尿病组 ( 11例 )。这些研究对象在完成减少样本数的IVGTT时同步测定 12个时相的血清胰岛素、瘦素和FFA水平。结果 血清瘦素在试验的 3h内平稳分泌 ;血FFA在糖负荷后的分泌曲线大致呈“U”型。相关分析显示瘦素和FFA在 3h内的平均水平与空腹血糖值无关。瘦素与胰岛素的相关性 (r =0 .77,P <0 .0 0 1)在扣除FFA因素后削弱 (r =0 .67,P <0 .0 0 1)。FFA与胰岛素的相关性 (r =0 .45 ,P <0 .0 5 )在扣除血糖因素后略有增强 (r =0 .47,P <0 .0 5 )。而瘦素与FFA的相关性 (r =0 .46,P <0 .0 5 )扣除胰岛素因素后消失 (P>0 .0 5 )。结论 糖负荷后的血清FFA浓度的变化比瘦素显著。空腹葡萄糖浓度不改变血清瘦素和FFA的平均分泌水平。胰岛素浓度可影响瘦素和FFA在糖负荷后的分泌幅度 。

Objective To investigate the factors which may affect the secretions of human leptin and free fatty acids (FFA) by measuring plasma glucose, serum insulin, leptin and FFA levels during reduced sample number intravenous glucose tolerance tests (IVGTT) in the subjects with different status of insulin resistance and β cell function. Methods According to oral glucose tolerance test, 7 normal, 10 overweight/obese individuals, 12 subjects with impaired glucose tolerance (IGT) and 11 with type 2 diabetes mellitus (DM) were recruited. During IVGTT, serum insulin, leptin and FFA levels at 12 time points were simultaneously measured. Results Compared to the stable secretion of leptin, during 180 min in the IVGTT, the FFA secretion showed a 'U' shape profile. The correlation analysis showed that the average serum leptin and FFA levels in 3 h were independent to fasting plasma glucose concentration. The partial correlation coefficient of leptin and insulin decreased after being adjusted for FFA (before r=0.77, P<0.001; after r=0.67, P<0.001), whereas the partial correlation coefficient of FFA and insulin increased after being adjusted for glucose (before r=0.45, P<0.05; after r=0.47, P<0.05). After being adjusted for insulin, the partial correlation of leptin and FFA disappeared (before r=0.46, P<0.05; after P>0.05). Conclusion The changes of serum FFA levels in IVGTT are more significant than those of leptin after glucose loading. Fasting plasma glucose levels do not significantly affect the average serum levels of leptin and FFA. On the contrary, insulin manifests such action but does not affect the secretion profile of these parameters.