title: Post-glucose-load urinary C-peptide and glucose concentration obtained during OGTT do not affect oral minimal model-based plasma indices.
abstract: The purpose of this study was to investigate how renal loss of both C-peptide and glucose during oral glucose tolerance test (OGTT) relate to and affect plasma-derived oral minimal model (OMM) indices. All individuals were recruited during family screening between August 2007 and January 2011 and underwent a 3.5-h OGTT, collecting nine plasma samples and urine during OGTT. We obtained the following three subgroups: normoglycemic, at risk, and T2D. We recruited South Asian and Caucasian families, and we report separate analyses if differences occurred. Plasma glucose, insulin, and C-peptide concentrations were analyzed as AUCs during OGTT, OMM estimate of renal C-peptide secretion, and OMM beta-cell and insulin sensitivity indices were calculated to obtain disposition indices. Post-glucose load glucose and C-peptide in urine were measured and related to plasma-based indices. Urinary glucose corresponded well with plasma glucose AUC (Cau r = 0.64, P < 0.01; SA r = 0.69, P < 0.01), S I (Cau r = -0.51, P < 0.01; SA r = -0.41, P < 0.01), Φ dynamic (Cau r = -0.41, P < 0.01; SA r = -0.57, P < 0.01), and Φ oral (Cau r = -0.61, P < 0.01; SA r = -0.73, P < 0.01). Urinary C-peptide corresponded well to plasma C-peptide AUC (Cau r = 0.45, P < 0.01; SA r = 0.33, P < 0.05) and OMM estimate of renal C-peptide secretion (r = 0.42, P < 0.01). In general, glucose excretion plasma threshold for the presence of glucose in urine was ~10-10.5 mmol L(-1) in non-T2D individuals, but not measurable in T2D individuals. Renal glucose secretion during OGTT did not influence OMM indices in general nor in T2D patients (renal clearance range 0-2.1 %, with median 0.2 % of plasma glucose AUC). C-indices of urinary glucose to detect various stages of glucose intolerance were excellent (Cau 0.83-0.98; SA 0.75-0.89). The limited role of renal glucose secretion validates the neglecting of urinary glucose secretion in kinetic models of glucose homeostasis using plasma glucose concentrations. Both C-peptide and glucose in urine collected during OGTT might be used as non-invasive measures for endogenous insulin secretion and glucose tolerance state.
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Sjaam
authors.initials: S
authors.lastname: Jainandunsing
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: J L Darcos
authors.initials: JL
authors.lastname: Wattimena
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Trinet
authors.initials: T
authors.lastname: Rietveld
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Joram N I
authors.initials: JN
authors.lastname: van Miert
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Eric J G
authors.initials: EJ
authors.lastname: Sijbrands
authors.affiliation: Department of Internal Medicine, Erasmus MC - University Medical Center Rotterdam, Room Na-512, PO-box 2040, 3000 CA, Rotterdam, The Netherlands. f.derooij@erasmusmc.nl.
authors.forename: Felix W M
authors.initials: FW
authors.lastname: de Rooij
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D002096:C-Peptide / Q000652:urine*; D003924:Diabetes Mellitus, Type 2 / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D005951:Glucose Tolerance Test; D006029:Glycosuria; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012372:ROC Curve
chemical_list: D015415:Biomarkers; D002096:C-Peptide
keywords: C-peptide; Glucose; OGTT; Oral minimal model; South Asian; Type 2 diabetes