High sensitivity glp 1 active elisa kit

Blood sampling was conducted by vein cannula. Serum insulin was determined by photometry (Beckman Coulter, Brea, CA, USA). Glucose was measured using hexokinase method (Beckman Coulter, Brea, CA, USA). Blood samples to analyze active GLP-1 were withdrawn directly into BD P800 plasma tubes (Becton Dickinson, Heidelberg, Germany) containing an inhibitory mix (i.e., Dipeptidyl peptidase 4 inhibitor), kept in ice and centrifuged in a refrigerated centrifuge within 10 min. Aliquots were stored at −80 °C. Circulating levels of active GLP-1 (7-36) were quantified at the University of Tübingen using the chemiluminescent high sensitivity GLP-1 Active ELISA Kit (#EZGLPHS-35K, Merck Millipore, Darmstadt, Germany). Measurements were performed in duplicate on the Glo-Max Luminometer (Promega GmbH, Mannheim, Germany) applying the five-parameter logistic (GraphPad Prism Software, La Jolla, CA, USA) according to the manufacturer’s instructions. Urinary c-peptide was analyzed with luminescence immunoassay.

Blood samples were collected after 6–8 h fasting. Plasma glucose levels were measured using a dextrometer (Stat strip XP2, Nipro, Osaka, Osaka, Japan). Hemoglobin A1c (HbA1c) and plasma lipid levels were determined using a latex-enhanced immunoassay and an enzymatic colorimetric assay, respectively (Cobas, Roche Diagnostics Japan, Minato, Tokyo, Japan). Plasma active GLP-1 levels were measured by ELISA (High Sensitivity GLP-1 Active ELISA Kit, EMD Millipore, Billerica, MA, USA).