Routine biochemical parameters (glucose, HbA1C, insulin, C-peptide) were measured by an automated analyzer Cobas 8000 (Roche) on the day of blood collection. Concentrations of incretins and glucagon were measured in sample aliquots stored at − 80 °C for no longer than 6 months.
Glucose levels were determined using the hexokinase method (GLUC3, Roche Diagnostics GmbH, Mannheim, Germany). Levels of HbA1C were measured by ion exchange chromatography using the Arkray Adams HA-8180 V analyzer (Arkray Corporation, Kyoto, Japan). Insulin and C-peptide levels were determined with commercially available kits (Immunotech, Marseille, France) using an immunoradiometric assay with specific antibodies. Based on fasting glucose and insulin levels the homeostasis model assessment of β-cell function (HOMA-β), homeostasis model assessment of insulin resistance (HOMA-IR) indexes [22 (link)], and quantitative insulin sensitivity check index (QUICKI) [23 (link)] were calculated.
Plasma glucagon, GLP-1, and GIP concentrations were measured by commercial multiplex assay (Human Metabolic Hormone Magnetic Bead Panel, HMHEMAG- 34 K, Merck Millipore, USA). Sensitivity was 13.0 pg/mL for glucagon, 1.2 pg/mL for GLP-1 and 0.6 pg/mL for GIP. Intra- and inter-assay variabilities for the kits were < 10% and 15%, respectively.
Glucose levels were determined using the hexokinase method (GLUC3, Roche Diagnostics GmbH, Mannheim, Germany). Levels of HbA1C were measured by ion exchange chromatography using the Arkray Adams HA-8180 V analyzer (Arkray Corporation, Kyoto, Japan). Insulin and C-peptide levels were determined with commercially available kits (Immunotech, Marseille, France) using an immunoradiometric assay with specific antibodies. Based on fasting glucose and insulin levels the homeostasis model assessment of β-cell function (HOMA-β), homeostasis model assessment of insulin resistance (HOMA-IR) indexes [22 (link)], and quantitative insulin sensitivity check index (QUICKI) [23 (link)] were calculated.
Plasma glucagon, GLP-1, and GIP concentrations were measured by commercial multiplex assay (Human Metabolic Hormone Magnetic Bead Panel, HMHEMAG- 34 K, Merck Millipore, USA). Sensitivity was 13.0 pg/mL for glucagon, 1.2 pg/mL for GLP-1 and 0.6 pg/mL for GIP. Intra- and inter-assay variabilities for the kits were < 10% and 15%, respectively.
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