Specificity and sensitivity of commercially available assays for glucagon-like peptide-1 (GLP-1): implications for GLP-1 measurements in clinical studies
Article first published online: 22 JUL 2014
© 2014 John Wiley & Sons Ltd
Diabetes, Obesity and Metabolism
Volume 16, Issue 11, pages 1155–1164, November 2014
How to Cite
Bak, M. J., Wewer Albrechtsen, N. J., Pedersen, J., Knop, F. K., Vilsbøll, T., Jørgensen, N. B., Hartmann, B., Deacon, C. F., Dragsted, L. O. and Holst, J. J. (2014), Specificity and sensitivity of commercially available assays for glucagon-like peptide-1 (GLP-1): implications for GLP-1 measurements in clinical studies. Diabetes, Obesity and Metabolism, 16: 1155–1164. doi: 10.1111/dom.12352
- Issue published online: 8 OCT 2014
- Article first published online: 22 JUL 2014
- Accepted manuscript online: 7 JUL 2014 12:17PM EST
- Manuscript Accepted: 30 JUN 2014
- Manuscript Revised: 23 MAY 2014
- Manuscript Received: 8 MAR 2014
- Danish Ministry of Science, Technology and Innovation
- enzyme-linked immunosorbent assay;
- glucagon-like peptide-1;
To evaluate the performances of commercially available glucagon-like peptide-1 (GLP-1) assays and the implications for clinical studies.
Known concentrations (5–300 pmol/l) of synthetic GLP-1 isoforms (GLP-1 1-36NH2, 7-36NH2, 9-36NH2, 1-37, 7-37 and 9-37) were added to the matrix (assay buffer) supplied with 10 different kits and to human plasma, and recoveries were determined. Assays yielding meaningful results were analysed for precision and sensitivity by repeated analysis and ability to discriminate low concentrations. Endogenous GLP-1 levels in clinical samples were assessed using three commercial kits.
The USCN LIFE assay detected none of the GLP-1 isoforms. The active GLP-1 enzyme-linked immunosorbent assays (ELISAs) from Millipore and DRG appeared identical and were specific for intact GLP-1 in buffer and plasma. The Meso Scale Discovery (MSD) total GLP-1 kit detected all six GLP-1 isoforms, although recovery of non-active forms was incomplete, especially in plasma. Millipore total GLP-1 ELISA kit detected all isoforms in buffer, but mainly amidated forms in plasma. The Alpco, Phoenix and Bio-Rad kits detected only amidated GLP-1, but the Alpco kit had a limited measurement range (30 pmol/l), the Phoenix kit had incomplete recovery in plasma and the Bio-Rad kit was insensitive (detection limit in plasma 40 pmol/l). The pattern of postprandial GLP-1 responses in clinical samples was similar between the kits tested, but the absolute concentrations measured varied.
The specificity and sensitivity of commercially available kits for the analysis of GLP-1 levels vary considerably. This should be taken into account when selecting which assay to use and when comparing data from different studies.