New Point-of-Care C Peptide Test Shows Promise

This article is part of Endocrinology Advisor’s coverage of the American Diabetes Association’s 77th Scientific Sessions (ADA 2017), taking place in San Diego, CA. Our staff will report on medical research and technological advances in diabetes and diabetes education, conducted by experts in the field. Check back regularly for more news from ADA 2017.

Findings regarding a quantitative point-of-care (POC) C peptide test developed by DiabetOmics, Inc., an Oregon-based medical testing company, were presented at the American Diabetes Association (ADA) 77th Scientific Sessions held June 9-13, 2017 in San Diego, California.¹

C peptide is released in equal amounts to insulin, and levels are unaffected by insulin therapy, making it a valuable clinical tool and marker of functional beta-cell mass in patients with diabetes.² The absence of C-peptide indicates absolute insulin deficiency and the need for type 1 diabetes (T1D) management. In patients with type 2 diabetes (T2D), the test can guide treatment based on changes in insulin secretion capacity. 

For example, C peptide levels can identify residual beta-cell function, which could lead to the use of new immunotherapies or beta-cell sparing interventions in these patients. In addition, the test can detect impending insulinopenia in patients with T2D or latent autoimmune diabetes (type 1.5 diabetes).¹ 

However, because C peptide testing is laboratory-based, its access is limited in low-resource settings and underserved patient populations. The POC test for C peptide is an attempt to bridge this gap in patient care. 

The researchers at DiabetOmics, Inc. created the assay using “an optimized strip design comprised of a gold-conjugated detection antibody and immobilized capture and control antibodies in test and reference lines.” This allows for the measurement of levels as low as 0.2 ng/mL from a 20-ul fingerstick blood sample, with analytical sensitivity ranging from .013 to 0.9 ng/mL. 

To evaluate the correlation between the POC test and a highly sensitive C-Peptide ELISA test, researchers tested 120 clinical samples from patients with type 1 and type 2 diabetes with a broad range of C peptide levels. A correlation of r=0.93 was observed between the 2 tests. 

These results suggest that the POC test could increase the ease and availability of C peptide testing and “facilitate the expanded use of C peptide in evaluating disease risk and progression across the entire spectrum of diabetes,” they concluded.