Yan-Do Richard, MacDonald Patrick E
Alberta Diabetes Institute and Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada.
Endocrinology. 2017 May 1;158(5):1064-1073. doi: 10.1210/en.2017-00148.
The onset and/or progression of type 2 diabetes (T2D) can be prevented if intervention is early enough. As such, much effort has been placed on the search for indicators predictive of prediabetes and disease onset or progression. An increasing body of evidence suggests that changes in plasma glycine may be one such biomarker. Circulating glycine levels are consistently low in patients with T2D. Levels of this nonessential amino acid correlate negatively with obesity and insulin resistance. Plasma glycine correlates positively with glucose disposal, and rises with interventions such as exercise and bariatric surgery that improve glucose homeostasis. A role for glycine in the regulation of glucose, beyond being a potential biomarker, is less clear, however. Dietary glycine supplementation increases insulin, reduces systemic inflammation, and improves glucose tolerance. Emerging evidence suggests that glycine, a neurotransmitter, also acts directly on target tissues that include the endocrine pancreas and the brain via glycine receptors and as a coligand for N-methyl-d-aspartate glutamate receptors to control insulin secretion and liver glucose output, respectively. Here, we review the current evidence supporting a role for glycine in glucose homeostasis via its central and peripheral actions and changes that occur in T2D.
如果干预足够早，2型糖尿病（T2D）的发病和/或进展是可以预防的。因此，人们付出了很多努力来寻找能够预测糖尿病前期以及疾病发病或进展的指标。越来越多的证据表明，血浆甘氨酸的变化可能就是这样一种生物标志物。T2D患者的循环甘氨酸水平一直较低。这种非必需氨基酸的水平与肥胖和胰岛素抵抗呈负相关。血浆甘氨酸与葡萄糖处置呈正相关，并随着运动和减肥手术等改善葡萄糖稳态的干预措施而升高。然而，甘氨酸在葡萄糖调节中的作用，除了作为一种潜在的生物标志物外，尚不清楚。膳食补充甘氨酸可增加胰岛素、减轻全身炎症并改善葡萄糖耐量。新出现的证据表明，作为一种神经递质，甘氨酸还可通过甘氨酸受体直接作用于包括内分泌胰腺和大脑在内的靶组织，并作为N-甲基-D-天冬氨酸谷氨酸受体的共配体，分别控制胰岛素分泌和肝脏葡萄糖输出。在此，我们综述了目前支持甘氨酸通过其在中枢和外周的作用以及在T2D中发生的变化来维持葡萄糖稳态的证据。
