Evaluation of the analytical performances of the Cobas c513 analyser for HbA1c assay

Association of Lipoprotein and Apolipoprotein Ratios With Glycemic Levels in Individuals With Prediabetes: A Case-Control Study

BACKGROUND

 Prediabetes is defined as a hyperglycemic state between normal glucose metabolism and diabetes mellitus. It is also recognized as a predisposing factor for cardiovascular disease. Apolipoprotein is a constituent of lipoproteins, and its ratio levels (ApoB/ApoA1 ratio) are considered an independent risk factor for cardiovascular diseases. This study aimed to evaluate the apolipoprotein ratio (ApoB/ApoA1 ratio) and lipoprotein ratio (low-density lipoprotein cholesterol/high-density lipoprotein cholesterol (LDL-C/HDL-C) ratio) in prediabetes in relation to glycemic levels and establish the association between apolipoprotein and lipoprotein ratios in prediabetic individuals and their glycemic levels.

METHODOLOGY

 A case-control study was conducted among 150 participants, 75 with prediabetes and 75 apparently healthy individuals (with no prediabetes or diabetes), from January 1, 2023 to December 30, 2023. The parameters involved are fasting serum glucose, insulin, blood HbA1c%, HDL-C, LDL-C, apolipoprotein A, apolipoprotein B, and lipoprotein(a) (Lp(a)), measured using different principles.

RESULTS

Prediabetes was more predominant in males (58.7%), particularly those aged over 40 years (74.7%). The mean Lp(a) (46.18±11.66 mg/dl), LDL-C/HDL-C ratio (1.74±0.96), and ApoB/ApoA ratio (1.10±0.62) were significantly higher among prediabetic individuals. Moreover, these ratios were insignificantly higher in prediabetic individuals with HbA1c level (5.8-6.4%) and fasting glucose level (100-125 mg/dl) than those with lower levels.

CONCLUSIONS

Prediabetic individuals exhibited a notably elevated average level of Lp(a), as well as increased mean ApoB/ApoA1 ratio and mean LDL-C/HDL-C ratio compared to individuals who were apparently healthy.

HbA1c and biomarkers of diabetes mellitus in Clinical Chemistry and Laboratory Medicine: ten years after

Since its discovery in the late 1960s, HbA_1c has proven to be a major biomarker of diabetes mellitus survey and diagnosis. Other biomarkers have also been described using classical laboratory methods or more innovative, non-invasive ones. All biomarkers of diabetes, including the historical glucose assay, have well-controlled strengths and limitations, determining their indications in clinical use. They all request high quality preanalytical and analytical methodologies, necessitating a strict evaluation of their performances by external quality control assessment trials. Specific requirements are needed for point-of-care testing technologies. This general overview, which describes how old and new tools of diabetes mellitus biological survey have evolved over the last decade, has been built through the prism of papers published in Clinical Chemistry and Laboratory Medicine during this period.

Oral glucose tolerance test does not affect degree of hemoglobin glycation as measured by routine assay

BACKGROUND

Hemoglobin A1c (HbA1c) is an accurate index of fluctuation in glycemia over the 2-3 months prior to quantitative assessment. During this time, hemoglobin (Hb) slowly glycates until it shows the properties of advanced glycation end-products. Glycation kinetics is intensified by prolonged glucose exposure. In subjects undergoing oral glucose tolerance testing (OGTT), immediately after ingestion, glucose is ostensibly transported by the glucose transporter 1 (GLUT1) to erythrocyte corpuscular hemoglobin. The earliest significant measurable level of hemoglobin glycation associated with this transportation is still not clear.

SUBJECTS AND METHODS

We attempted to explore the early impact of short-term glucose load on HbA1c levels, because it is now known that transmembrane GLUT1-mediated glucose transport occurs immediately. A total of 88 participants (46 patients and 42 clinically healthy controls) underwent fasting plasma glucose quantitation during an OGTT. HbA1c, revealed by a monoclonal anti-glycation epitope antibody and adiponectin, was quantitated before (T0) and 2 hours (T120) after 80 g glucose ingestion.

RESULTS

Wilcoxon test revealed that the HbA1c values did not significantly vary (P=0.15) during the OGTT, whereas glucose concentration varied strongly between T0 and T120.

DISCUSSION

It is well known that quantitative estimation of HbA1c is informative for clinical care, independently of glucose level. The molecular mechanisms and dynamics by which glucose enters/exits red blood cells are incompletely known and may differ between individuals. We here show, for the first time, that HbA1c levels do not significantly increase during OGTT, supporting the view that non-enzymatic glycation of hemoglobin occurs slowly and that glycation during the 2 hours of an OGTT is insignificant.

Faster HbA1c Turnaround Times Using a Dedicated Analyzer Based on Turbidimetric Inhibition Immunoassay Technology

INTRODUCTION

The Roche Cobas c513 (c513) is a dedicated stand-alone high throughput HbA1c analyzer. We evaluated the performance and the difference in turnaround times (TAT) of the c513 against our Cobas 8000 c502 (c502).

METHODS

We assessed the linearity and precision of the c513, and its agreement (Deming regression and Bland-Altman analysis) with the c502 assay. We compared TAT for these analyzers for a single run of 50 samples and for all samples run over 2 comparable time periods.

RESULTS

The c513 assay was linear from 4.4-18.3% HbA1c. Interassay precision (CV%) was 1.2 and 0.8 at HbA1c levels of 5.7 and 10.5%, respectively. The c513 assay showed excellent concordance with the c502 assay (r = 0.997) with no significant difference between methods by Bland-Altman analysis (mean difference = 0.021% HbA1c, P = 0.1422). The c513 took 17 min to analyze 50 samples, compared to 40 min on the c502. Over comparable 2-month periods, 90% of samples requiring HbA1c tests only were completed under 25 min (c513) vs 30-35 min (c502). For tubes sharing complete blood count (CBC) testing with HbA1c, the 90th percentile TAT was 35-40 min (c513) compared to 45-50 min (c502).

CONCLUSION

The c513 assay performs well with excellent correlation to the c502 assay. The improved TAT of the c513 is suitable when there are demands for rapid HbA1c results and it may forestall requests for point-of-care testing. It is also attractive to sites with heavy workloads with a claimed throughput of 400 tests / h.