Impact of routine clinic measurement of serum C‐peptide in people with a clinician‐diagnosis of type 1 diabetes

• Published in: Diabetic medicine 2021-07, Vol.38 (7), p.e14449-n/a
• Main Authors: Foteinopoulou, Evgenia, Clarke, Catriona A. L., Pattenden, Rebecca J., Ritchie, Stuart A., McMurray, Emily M., Reynolds, Rebecca M., Arunagirinathan, Ganesan, Gibb, Fraser W., McKnight, John A., Strachan, Mark W. J.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biomarkers - blood; C-Peptide - blood; C‐peptide; Diabetes; Diabetes mellitus (insulin dependent); Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 2 - diagnosis; Diagnosis; Genetic screening; Humans; Insulin; Medical diagnosis; misclassification; monogenic diabetes; Peptides; reclassification; type 1 diabetes; type 1 diabetes genetic risk score; type 2 diabetes; Young Adult
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/dme.14449

ABSTRACT Aims/hypothesis The aim of this study was to determine the impact of the routine use of serum C‐peptide in an out‐patient clinic setting on individuals with a clinician‐diagnosis of type 1 diabetes. Methods In this single‐centre study, individuals with type 1 diabetes of at least 3 years duration were offered random serum C‐peptide testing at routine clinic review. A C‐peptide ≥200 pmol/L prompted further evaluation of the individual using a diagnostic algorithm that included measurement of islet cell antibodies and genetic testing. Where appropriate, a trial of anti‐diabetic co‐therapies was considered. Results Serum C‐peptide testing was performed in 859 individuals (90% of the eligible cohort), of whom 114 (13.2%) had C‐peptide ≥200 pmol/L. The cause of diabetes was reclassified in 58 individuals (6.8% of the tested cohort). The majority of reclassifications were to type 2 diabetes (44 individuals; 5.1%), with a smaller proportion of monogenic diabetes (14 individuals; 1.6%). Overall, 13 individuals (1.5%) successfully discontinued insulin, while a further 16 individuals (1.9%) had improved glycaemic control following the addition of co‐therapies. The estimated total cost of the testing programme was £23,262 (~€26,053), that is, £27 (~€30) per individual tested. In current terms, the cost of prior insulin therapy in the individuals with monogenic diabetes who successfully stopped insulin was approximately £57,000 (~€64,000). Conclusions/interpretation Serum C‐peptide testing can easily be incorporated into an out‐patient clinic setting and could be a cost‐effective intervention. C‐peptide testing should be strongly considered in individuals with a clinician‐diagnosis of type 1 diabetes of at least 3 years duration. Click here to access the podcast for this paper.