Hexokinase

OGTT’s were performed following a minimum 8 hour fast. Glucose was administered at a dose of 1.75 g/kg (maximum 75g) and samples for measurement of glucose, insulin, and c-peptide were collected at 0, 10, 20, 30, 60, 90, and 120-minutes. OGTT classifications were as follows: NGT was a fasting glucose of <100 mg/dL, 1hG <200 mg/dL, and 2hG <140 mg/dL; AGT was a fasting glucose of 100–125 mg/dL, 1hG ≥200 mg/dL, and/or 2hG 140–199 mg/dL; CFRD was a fasting glucose ≥126 mg/dL and/or a 2hG ≥200 mg/dL ^{7 (link)}. Laboratory assays were performed by the CTRC core laboratories. Serum glucose was analyzed by hexokinase with an intra-assay variability of 0.67%, an inter-assay variability of 1.44%, and a sensitivity of 10 mg/dL (Beckman Coulter, Brea, CA); serum insulin was analyzed by chemiluminescent immunoassay with an intra-assay variability of 1.60%, an inter-assay variability of 2.80%, and a sensitivity of 0.5 uIU/mL (Beckman Coulter, Brea, CA); and c-peptide was analyzed by Elisa with an intra-assay variability of 4.80%, an inter-assay variability of 4.80%, and a sensitivity of 0.1 ng/mL (Mercodia, Uppsala, Sweden).