A UHPLC/MS/MS method for the analysis of active and inactive forms of GLP-1 and GIP incretins in human plasma

Glucagon-like peptide (GLP)-1 and the glucose-dependent insulinotropic peptide (GIP) are incretin hormones that regulate the nutrient-stimulated insulin secretion from pancreatic β-cells. Their low plasma concentrations and rapid clearance pose certain methodological challenges for their detection and quantification. The currently available immunomediated techniques to monitor these hormones overestimate, to some extent, their actual concentration. Hence, the present study is aimed at developing a robust and reliable methodology for the identification and quantification of active and inactive forms of the incretins GLP-1 and GIP, in human plasma, by UHPLC-ESI-QqQ-MS/MS. A comparative study of different SPE cartridges was carried out, being identified OASIS HLB as the most efficient one, with recoveries up to 80%. The method provides adequate linearity, from 4.88 to 1250 nM, and low intervals of LOD and LOQ for each analyte (ranges from 0.01 to 3.42 nM and from 0.10 to 34.17 nM, respectively). The methodology described was validated upon a clinical trial with overweight subjects (n = 20) (ClinicalTrials.gov NCT04016337), showing the capacity of the newly developed methodology to detect the augment of the plasma concentration of both GLP-1_7-36 and GLP-1_9-36 between 30 and 60 min after the consumption of a sucrose sweetened fruit-based beverage, while the plasma concentration of GIP remained in levels lower than the LOQ. The proposed methodology provides further insights into the mechanisms of action of bioactive compounds and food components in the frame of the glycemic control and would contribute to the assessment of the efficacy of antidiabetic drugs.