Analysis of glucagon-like peptide 1; what to measure?

• Published in: Clinica chimica acta Vol. 412; no. 13; pp. 1191 - 1194
• Main Authors: Heijboer, Annemieke C., Frans, Anneke, Lomecky, Marie, Blankenstein, Marinus A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 11.06.2011
• Subjects: Analysis; Clinical Chemistry Tests - methods; Dipeptidyl Peptidase 4 - metabolism; Dipeptidyl-Peptidase IV Inhibitors - pharmacology; DPP4 inhibitor; Enzyme-Linked Immunosorbent Assay; Glucagon-like peptide 1; Glucagon-Like Peptide 1 - analysis; Gut hormone; Humans; Immunoassay; Postprandial Period; Immunoassay; Gut hormone; DPP4 inhibitor; Glucagon-like peptide 1; Analysis
• ISSN: 0009-8981; 1873-3492; 1873-3492
• DOI: 10.1016/j.cca.2011.03.010

Glucagon-like peptide 1 (GLP-1) is a gut hormone which acts as an incretin and is therefore of major interest in treatment of type II diabetes mellitus. GLP-1 circulates in many different forms, some of which are biologically active and others are not. Our hypothesis was that various methods to measure GLP-1 detect different forms of GLP-1, which may cause confusion when comparing results. We compared three assays, the GLP-1 (active) ELISA (Linco research; ELISA LINCO), GLP-1 (total) RIA (Linco research; RIA LINCO) and the total GLP-1 RIA developed by the group of Holst (RIA HOLST) on specimens obtained during meal studies. In addition, we studied the effect of addition of a DPP-4 inhibitor. The correlation between RIA LINCO and ELISA LINCO was highest (r = 0.76; n = 35; p < 0.01), whereas results of RIA HOLST correlated less with those of RIA LINCO and ELISA LINCO (r = 0.35 and 0.39 respectively; n = 35; p < 0.05). GLP-1 results measured with ELISA LINCO were higher (median 28%; p < 0.001) upon addition of the DPP-4 inhibitor. Two commercially available GLP-1 assays do not necessarily give results equal to the well-defined GLP-1 assay developed in Copenhagen. Absolute values are also different due to differences in standardisation. Moreover, assays detect different forms of GLP-1, which hampers comparison to published data.