title: Comparison of plasma active glucagon-like peptide-1 (GLP-1) levels assayed with or without plasma extraction in non-diabetic men.
abstract: Recently, interference from cross-reacting peptides in plasma has been recognized as being responsible for inter-subject differences in active glucagon-like peptide-1 (GLP-1) values.  An ethanol or solid-phase extraction step could reduce such interference.  A working group of the Japan Diabetes Society now recommends the inclusion of an extraction step when measuring active GLP-1 values.  We measured the active GLP-1 levels of 200 specimens derived from 10 subjects using both methods and compared the results.  The active GLP-1 levels measured by extraction method for 169 specimens with values greater than 2.0 pM tended to be lower than those by direct method.  However, the correlation between the GLP-1 levels measured by extraction and direct method was r=0.9225 (p < 0.0001).  In one case, the active GLP-1 level obtained using the extraction method was significantly lower than that obtained using the direct method.  Therefore, though there is a good correlation between the two methods, extraction is recommended for more accurate active GLP-1 measurements.
authors.affiliation: Department of Endocrinology and Metabolism, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan.
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Masuda
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aoki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Terauchi
mesh_terms: D000328:Adult; D053000:Analytic Sample Preparation Methods; D004797:Enzyme-Linked Immunosorbent Assay; D000431:Ethanol / Q000737:chemistry; D052216:Glucagon-Like Peptide 1 / Q000097:blood*; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D012997:Solvents / Q000737:chemistry
chemical_list: D012997:Solvents; D000431:Ethanol; D052216:Glucagon-Like Peptide 1