Circulating Unmethylated Insulin DNA As a Biomarker of Human Beta Cell Death: A Multi-laboratory Assay Comparison

J Clin Endocrinol Metab. 2020 Mar 1;105(3):781-791. doi: 10.1210/clinem/dgaa008.


Context: There is an unmet need for biomarkers of pancreatic beta-cell death to improve early diagnosis of type 1 diabetes, enroll subjects into clinical trials, and assess treatment response. To address this need, several groups developed assays measuring insulin deoxyribonucleic acid (DNA) with unmethylated CpG sites in cell-free DNA. Unmethylated insulin DNA should be derived predominantly from beta-cells and indicate ongoing beta-cell death.

Objective: To assess the performance of three unmethylated insulin DNA assays.

Design and participants: Plasma or serum samples from 13 subjects undergoing total pancreatectomy and islet autotransplantation were coded and provided to investigators to measure unmethylated insulin DNA. Samples included a negative control taken post-pancreatectomy but pretransplant, and a positive control taken immediately following islet infusion. We assessed technical reproducibility, linearity, and persistence of detection of unmethylated insulin DNA for each assay.

Results: All assays discriminated between the negative sample and samples taken directly from the islet transplant bag; 2 of 3 discriminated negative samples from those taken immediately after islet infusion. When high levels of unmethylated insulin DNA were present, technical reproducibility was generally good for all assays.

Conclusions: The measurement of beta cell cell-free DNA, including insulin, is a promising approach, warranting further testing and development in those with or at-risk for type 1 diabetes, as well as in other settings where understanding the frequency or kinetics of beta cell death could be useful.

Keywords: Beta cell; cell-free DNA; islet transplantation; type 1 diabetes.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biological Assay / standards
  • Biomarkers / analysis
  • Biomarkers / blood*
  • Cell Death* / genetics
  • Cell-Free Nucleic Acids / analysis
  • Cell-Free Nucleic Acids / blood*
  • DNA Methylation
  • Female
  • Humans
  • Insulin / blood
  • Insulin / genetics*
  • Insulin-Secreting Cells / metabolism
  • Insulin-Secreting Cells / physiology*
  • Laboratory Proficiency Testing
  • Male
  • Middle Aged
  • Reproducibility of Results


  • Biomarkers
  • Cell-Free Nucleic Acids
  • Insulin