Ann Lab Med 2018; 38(6): 530-537  https://doi.org/10.3343/alm.2018.38.6.530
Clinical Utility and Cross-Reactivity of Insulin and C-Peptide Assays by the Lumipulse G1200 System
Jongwon Oh, M.D.1, Jae Hyeon Kim, M.D.2, and Hyung-Doo Park, M.D., Ph.D.1
1Departments of Laboratory Medicine and Genetics and 2Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
Corresponding author: Hyung-Doo Park
https://orcid.org/0000-0003-1798-773X
Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
Tel: +82-2-3410-0290
Fax: +82-2-3410-2719
E-mail: nayadoo@hanmail.net
Received: November 16, 2017; Revised: May 21, 2018; Accepted: July 9, 2018; Published online: November 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

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Abstract
Background: Measurement of insulin and C-peptide concentrations is important for deciding whether insulin treatment is required in diabetic patients. We aimed to investigate the analytical performance of insulin and C-peptide assays using the Lumipulse G1200 system (Fujirebio Inc., Tokyo, Japan).
Methods: We examined the precision, linearity, and cross-reactivity of insulin and C-peptide using five insulin analogues and purified proinsulin. A method comparison was conducted between the Lumipulse G1200 and Roche E170 (Roche Diagnostics, Mannheim, Germany) systems in 200 diabetic patients on insulin treatment. Reference intervals for insulin and C-peptide concentrations were determined in 279 healthy individuals.
Results: For insulin and C-peptide assays, within-laboratory precision (% CV) was 3.78–4.14 and 2.89–3.35%, respectively. The linearity of the insulin assay in the range of 0–2,778 pmol/L was R2=0.9997, and that of the C-peptide assay in the range of 0–10 nmol/L was R2=0.9996. The correlation coefficient (r) between the Roche E170 and Lumipulse G1200 results was 0.943 (P <0.001) for insulin and 0.996 (P <0.001) for C-peptide. The mean differences in insulin and C-peptide between Lumipulse G1200 and the Roche E170 were 19.4 pmol/L and 0.2 nmol/L, respectively. None of the insulin analogues or proinsulin showed significant cross-reactivity with the Lumipulse G1200. Reference intervals of insulin and C-peptide were 7.64–70.14 pmol/L and 0.17–0.85 nmol/L, respectively.
Conclusions: Insulin and C-peptide tests on the Lumipulse G1200 show adequate analytical performance and are expected to be acceptable for use in clinical areas.
Keywords: C-peptide, Diabetes mellitus, Insulin, Lumipulse G1200, Performance



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