Introduction and Objective: Urinary C-peptide (UCP) could provide an easily measurable alternative to serum C-peptide (SCP). We aimed (i) to check over-time stability of UCP and (ii) to use UCP to predict homeostasis modelling assessment 2 indices of insulin resistance and beta cell function (HOMA2-IR and -B) and (iii) to be able to assign type 2 diabetes (T2D) subtypes using UCP.Methods: We analyzed a subset of the German Diabetes Study (GDS) with T2D (type 1 diabetes-related antibody absent) and people with normal glucose tolerance (NGT). Morning spot urine samples were stored at -20°C up to 15 years and measured for UCP and urinary creatinine by an electrochemiluminescence immunoassay. UCP stability over-time was assessed with linear regression modeling and Spearman correlation. Mixed linear models were used to predict SCP from UCP, age at diagnosis, sex and BMI, which are main confounders of UCP. HOMA2 indices were calculated from both SCP (HOMA2SCP) and predicted SCP (HOMA2pSCP). T2D-subtypes were calculated from both original Ahlqvist et al. classification using SCP and from predicted SCP. The dataset was split into training and testing sets using an 80:20 ratio. Resulting subtypes from using both HOMA2SCP and HOMA2pSCP were compared to each other.Results: This study included 488 T2D [age: 53 (IQR: 45-60) yrs., 35% female, BMI: 30 (IQR: 26-34) kg/m²] and 192 NGT [age: 47 (IQR: 30-56) yrs., 38% female, BMI: 26 (IQR: 24-29) kg/m²]. UCP remained stable over time 15 years, showing no decay (R = 0.04; p= 0.19). HOMA2pSCP strongly correlated with HOMA2SCP (HOMA2-IR: R = 0.81, p < 0.001; HOMA2-B: R = 0.83, p < 0.001). The cluster assignment based on predicted SCP achieved an accuracy of 79% (95% CI: 68-87, κ=0.64, p<0.001) in comparison to the ones derived using SCP.Conclusion: UCP can serve as a non-invasive alternative to SCP, even after prolonged sample storage. The use of UCP instead of SCP shows similar results for determining HOMA indices and T2D subtypes.
T. Londhe: None. I. Yurchenko: None. C. Binsch: None. K. Prystupa: None. S. Trenkamp: None. G. Heilmann: None. T. Mori: None. M. Heni: Advisory Panel; Amryt Pharma. Speaker’s Bureau; Amryt Pharma, AstraZeneca, Boehringer-Ingelheim. Advisory Panel; Boehringer-Ingelheim. Speaker’s Bureau; Lilly Diabetes, Novartis AG, Novo Nordisk, Sanofi. M. Roden: Research Support; Boehringer-Ingelheim. Advisory Panel; Echosens. Speaker’s Bureau; Madrigal Pharmaceuticals, Inc. Advisory Panel; MSD Life Science Foundation. Board Member; Novo Nordisk. Advisory Panel; TARGET PharmaSolutions, Inc. K. Bódis: None. R. Wagner: Speaker’s Bureau; Boehringer-Ingelheim, Novo Nordisk. Advisory Panel; Sanofi. Speaker’s Bureau; Sanofi. Advisory Panel; Lilly Diabetes.
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