Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA.
Diabetes. 2012 Nov;61(11):2728-33. doi: 10.2337/db11-1825. Epub 2012 Jun 25.
The incretin effect, reflecting the enhancement of postprandial insulin secretion by factors including the intestinal hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, increases in proportion to meal size. However, it is unknown whether the incretin effect is dependent on ambient glucose. The goal of this study was to determine the effect of plasma glycemia on the incretin effect. Thirteen healthy subjects consumed 50 g oral glucose solution mixed with d-xylose during fixed hyperglycemia at 8 and 10.5 mmol/L, on 3 separate days, twice at lower glycemia (LOW) and once at higher values (HIGH). The relative increase in insulin release after glucose ingestion at fixed hyperglycemia, a surrogate for the incretin effect, was similar among all three studies. The GLP-1 response to oral glucose was significantly lower at higher plasma glycemia, as was the appearance of d-xylose after the meal. Between the two LOW studies, the reproducibility of insulin release in response to intravenous glucose alone and intravenous plus ingested glucose was similar. These findings indicate that the incretin contribution to postprandial insulin release is independent of glycemia in healthy individuals, despite differences in GLP-1 secretion. The incretin effect is a reproducible trait among humans with normal glucose tolerance.
肠促胰岛素效应，反映了包括肠激素胰高血糖素样肽-1（GLP-1）和葡萄糖依赖性胰岛素释放肽在内的多种因素对餐后胰岛素分泌的增强作用，与进餐量成比例增加。然而，肠促胰岛素效应是否依赖于环境血糖尚不清楚。本研究旨在确定血糖对肠促胰岛素效应的影响。13 名健康受试者在固定高血糖（8 和 10.5mmol/L）下，于 3 天内分 3 次分别在较低血糖（LOW）和较高血糖（HIGH）时摄入 50g 口服葡萄糖溶液并混合二甲双胍。固定高血糖时，葡萄糖摄入后胰岛素释放的相对增加（肠促胰岛素效应的替代指标）在所有 3 项研究中相似。口服葡萄糖时 GLP-1 反应在较高血糖时显著降低，餐后二甲双胍的出现也降低。在 2 项 LOW 研究之间，单独给予静脉葡萄糖和静脉给予葡萄糖加口服葡萄糖时胰岛素释放的重现性相似。这些发现表明，在健康个体中，尽管 GLP-1 分泌存在差异，肠促胰岛素对餐后胰岛素分泌的贡献仍不依赖于血糖。肠促胰岛素效应是具有正常糖耐量的人类的一种可重现的特征。
