A comparative analysis of current С-peptide assays compared to a reference method: can we overcome inertia to standardization?

Objectives: C-peptide is an equimolar by-product of insulin biosynthesis. It is used clinically to assess insulin secretion and differentiate types of diabetes. However, the lack of standardization across assays limits its broader application.

Point-of-Care HbA1c in Clinical Practice: Caveats and Considerations for Optimal Use.

Hemoglobin A1c (A1C) is widely used for the diagnosis and management of diabetes. Accurate measurement of A1C is necessary for optimal clinical value. Assay standardization has markedly improved the accuracy and consistency of A1C testing.

Evaluation of interference from hemoglobin C, D, E and S traits on measurements of hemoglobin A1c by fifteen methods.

Background: Hemoglobin C, D Punjab, E or S trait can interfere with hemoglobin A1c (HbA1c) results. We assessed whether they affect results obtained with 15 current assay methods.

Methods: Hemoglobin AA (HbAA), HbAC, HbAD Punjab, HbAE and HbAS samples were analyzed on 2 enzymatic, 4 ion-exchange HPLC and 9 immunoassay methods.

Quantitation of glycated albumin by isotope dilution mass spectrometry.

Background: Glycated albumin is considered an alternative glycemic indicator in certain situations where HbA1c does not accurately reflect glycemic status. These patient cases are usually associated with decreased erythrocyte lifespan, gestational diabetes, or end-stage renal disease. The aim of our study was to develop an assay for absolute quantitation of glycated albumin based on isotope dilution liquid chromatography-mass spectrometry.

Continuous Glucose Monitoring and Use of Alternative Markers To Assess Glycemia in Chronic Kidney Disease.

Objective: In chronic kidney disease, glycated albumin and fructosamine have been postulated to be better biomarkers of glycemic control than HbA. We evaluated the accuracy, variability, and covariate bias of three biomarkers (HbA, glycated albumin, and fructosamine) compared with continuous glucose monitoring (CGM)-derived measurement of glycemia across estimated glomerular filtration rate (eGFR) in type 2 diabetes.

Research Design And Methods: A prospective cohort study was conducted of 104 participants with type 2 diabetes, 80 with eGFR <60 mL/min/1.

Hypoglycemia in People with Type 2 Diabetes and CKD.

Background And Objectives: Among people with diabetes mellitus, CKD may promote hypoglycemia through altered clearance of glucose-lowering medications, decreased kidney gluconeogenesis, and blunted counter-regulatory response. We conducted a prospective observational study of hypoglycemia among 105 individuals with type 2 diabetes treated with insulin or a sulfonylurea using continuous glucose monitors.

Design, Setting, Participants & Measurements: We enrolled 81 participants with CKD, defined as eGFR<60 ml/min per 1.

Accuracy and Precision of a Point-of-Care HbA1c Test.

Background: Point-of-care (POC) hemoglobin A1c (HbA1c) testing has advantages over laboratory testing, but some questions have remained regarding the accuracy and precision of these methods. The accuracy and the precision of the POC Afinion™ HbA1c Dx test were investigated.

Methods: Samples spanning the assay range were collected from prospectively enrolled subjects at three clinical sites.

The National Glycohemoglobin Standardization Program: Over 20 Years of Improving Hemoglobin A Measurement.

Background: Measurement of hemoglobin A1c (HbA) in the blood is integral to and essential for the treatment of patients with diabetes mellitus. HbA reflects the mean blood glucose concentration over the preceding 8 to 12 weeks. Although the clinical value of HbA was initially limited by large differences in results among various methods, the investment of considerable effort to implement standardization has brought about a marked improvement in analysis.

Multicenter assessment of a hemoglobin A1c point-of-care device for diagnosis of diabetes mellitus.

Objective: A multisite investigation compared the analytical performance of a point-of-care (POC) HbA1c device with multiple commonly used HbA1c laboratory methods and an NGSP (National Glycohemoglobin Standardization Program) reference method.

Research Design And Methods: The Afinion AS100 POC device analyzed HbA1c using 618 EDTA whole blood excess patient specimens with clinically indicated HbA1c testing. Results were compared to measurements across five clinical laboratories and the NGSP reference method.

Recognition of rare hemoglobin variants by hemoglobin A measurement procedures.

Background: Unrecognized hemoglobinopathies can lead to measured hemoglobin A (Hb A) concentrations that are erroneous or misleading. We determined the effects of rare hemoglobin variants on capillary electrophoresis (CE) and HPLC methods for measurement of Hb A.

Methods: We prospectively investigated samples in which Hb A was measured by CE during a 14-month period.

Implementing a Reference Measurement System for C-Peptide: Successes and Lessons Learned.

Background: Assessment of endogenous insulin secretion by measuring C-peptide concentrations is widely accepted. Recent studies have shown that preservation of even small amounts of endogenous C-peptide production in patients with type 1 diabetes reduces risks for diabetic complications. Harmonization of C-peptide results will facilitate comparison of data from different research studies and later among clinical laboratory results at different sites using different assay methods.

Higher degree of glycation of hemoglobin S compared to hemoglobin A measured by mass spectrometry: Potential impact on HbA1c testing.

Background: Glycated hemoglobin (GHb), reported as HbA1c, is used as marker of long-term glycemia for diabetic patients. HbA1c results from boronate affinity methods are generally considered to be unaffected by most hemoglobin variants; this assumes comparable glycation of variant and non-variant (HbAA) hemoglobins. In this report, glycation of HbA beta chain (βA) and HbS beta chain (βS) for the most common Hb variant trait (HbAS) are examined.

Effects of hemoglobin C, D, E and S traits on measurements of hemoglobin A1c by twelve methods.

Background: Hemoglobin C, D Punjab, E or S trait can interfere with hemoglobin A1c (HbA1c) results. We assessed whether they affect results obtained with 12 current assay methods.

Methods: Hemoglobin AA (HbAA), HbAC, HbAD Punjab, HbAE and HbAS samples were analyzed on one enzymatic, nine ion-exchange HPLC and two Capillary Electrophoresis methods.