A wide variety of methods, such as enzymatic methods, LC-MS, and LC-MS/MS, are currently available for the concentration determination of plasma glucose in studies of diabetes, obesity, exercise, etc. However, these methods rarely discriminate endogenous and exogenous glucose in plasma. A novel NMR strategy for discriminative quantification of the endogenous and exogenous glucose in plasma has been developed using an adapted isotope dilution ¹H–¹³C heteronuclear single-quantum correlation (ID-HSQC) with uniformly ¹³C-labeled glucose as a tracer of exogenous glucose. This method takes advantage of the distinct ¹H–¹³C chemical shifts of the hemiacetal group of the α-D-glucopyranose and makes use of the ¹³C–¹³C one-bond J-coupling (¹J_CC) in uniformly ¹³C-labeled glucose to differentiate the ¹H–¹³C HSQC signal of labeled glucose from that of its natural counterpart when data are acquired in high-resolution mode. The molar ratio between the endogenous and exogenous plasma glucose can then be calculated from the peak intensities of the natural and labeled glucose. The accuracy and precision of the method were evaluated using a series of standard mixtures of natural and uniformly ¹³C-labeled glucose with varied but known concentrations. Application of this method is demonstrated for the quantification of endogenous and exogenous glucose in plasma derived from healthy and diabetic cynomolgus monkeys. The results nicely agree with our previous LC-MS/MS results. Considering the natural abundance of ¹³C isotope at the level of 1.1% in endogenous glucose, comparable peak intensities of quantitatively measurable signals derived from natural and labeled glucose imply that the ID-HSQC can tolerate a significantly high ratio of isotope dilution, with labeled/natural glucose at ~ 1%. We expect that the ID-HSQC method can serve as an alternative approach to the biomedical or clinical studies of glucose metabolism.

目前，在糖尿病，肥胖症，运动等研究中，可使用多种方法（例如酶法，LC-MS和LC-MS / MS）测定血浆葡萄糖的浓度。但是，这些方法很少区分内源性和血浆中的外源葡萄糖。使用适合的同位素稀释¹ H– ¹³ C异核单量子相关性（ID-HSQC）和统一的¹³ C标记葡萄糖作为外源示踪剂，开发了一种用于区分血浆中内源性葡萄糖和外源性葡萄糖的新NMR策略。葡萄糖。该方法利用了α-D-吡喃葡萄糖半缩醛基团不同的¹ H– ¹³ C化学位移，并利用了统一采集¹³ C标记葡萄糖时的¹³ C– ¹³ C单键J耦合（¹ J _CC），以便在以高分辨率获取数据时将标记葡萄糖的¹ H– ¹³ C HSQC信号与其天然对应物区别开模式。内源性和外源性血浆葡萄糖之间的摩尔比然后可以根据天然和标记的葡萄糖的峰强度来计算。使用一系列自然和均一的标准混合物¹³评估了该方法的准确性和精密度。C标记的葡萄糖，浓度不同但已知。证实了该方法的应用，可用于定量测定来自健康和糖尿病食蟹猴的血浆中的内源性葡萄糖和外源性葡萄糖。结果与我们之前的LC-MS / MS结果非常吻合。考虑到内源性葡萄糖中¹³ C同位素的自然丰度为1.1％，从天然葡萄糖和标记葡萄糖获得的可定量测量信号的相当峰值强度暗示ID-HSQC可以耐受显着高比例的同位素稀释，标记/天然葡萄糖为〜1％。我们希望ID-HSQC方法可以作为葡萄糖代谢的生物医学或临床研究的替代方法。