Considerations about the use of glucometers in glucose tolerance tests
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Bernardo Alio Lavin-Gomez
To the Editor,
We read with great interest the paper by Fabre-Estremera, B. et al. [1]. Congratulations for your article, which addresses a very relevant issue in the field of clinical biochemistry. The article provides a comparative study of POCT glucometers for professional use and measurement at the core laboratory to test for glucose tolerance in the diagnosis of prediabetes and diabetes. The paper also examines connectivity to the patient’s medical record and the associated cost reduction. Glucose test is a fundamental parameter in the diagnosis and management of patients with diabetes or glucose intolerance. Accurate glucose measurement is crucial in both in-hospital and out-of-hospital clinical activity. However, glucometers are often designed for self-monitoring rather than for professional use. Please, find below some critical considerations that may contribute to the debate about this issue.
Pre-analytical sample handling: We find it noteworthy that, to prevent glycolysis during overload tests, containers with glycolysis inhibitors were not used at all time points. Current guidelines recommend using rapidly effective glycolysis inhibitor tubes. If this is not feasible, the tube containing the sample should be immediately placed in an ice-water slurry and centrifuged within 30 min from sample collection [2]. Failure to comply with these recommendations may lead to underestimate actual blood glucose concentrations due to post-collection glycolysis. This negatively affects comparative analysis of glucometers.
Correlation between glucose measurements. The authors found statistically significant differences in fasting glucose concentrations, with glucometers showing higher values. Although these differences could be explained by the pre-analytical considerations mentioned in the section above and in the Discussion by the authors, the behavior of the samples on the regression analysis is remarkable. The regression plots and Passing-Bablok regressions in the Supplementary Material show a clear tendency of differences to increase significantly as glucose values increase in the core laboratory. This suggests a systematic bias at higher glucose values, with POCT yielding lower values as compared to the laboratory. Do you have any hypothesis that may explain this unexpected trend?
Last, but not least, several studies suggest that abnormal hematocrit values may interfere with glucose readings on glucometers [3], [4], [5]. In general, low hematocrit values tend to lead to falsely elevated glucose readings, whereas high hematocrit values induce low glucose readings. In pediatric patients, it is recommended to establish a different range for the hematocrit based on age and sex. Thus, limits should range from 34 to 54 %, which may lead to significant differences [6]. However, most glucometers consider a constant hematocrit of 43 %, as recommended by the IFFC [7]. The same guidelines recommend using a constant factor of 11 % (F=1.11) for converting glucose in whole blood to glucose in plasma, a factor that is generally used by manufacturers.
Table 1 shows the results (unpublished data) obtained for glycemia in heparinized plasma measured in the core laboratory (Atellica®Solution-CH; Siemens-Healthineers, Erlangen, Germany) using the enzymatic method (glucose hexokinase), as compared to glycemia in heparinized whole blood measured on a professional glucometer that does not adjust the result to the real hematocrit of the patient and another commercially-available glucometer that concomitantly measures the hematocrit and performs separate conversion for each individual sample. When the glucose value was not adjusted for the actual hematocrit, a marked tendency was observed in the glucometer to yield higher glucose values at lower hematocrit values and vice versa (maximum rise of 23 % and maximum reductions of 19 %, respectively) despite the use of a constant conversion factor. The two glucometers complied with ISO 15197:2013 recommendations (at least 95 % of values within ±15 mg/dL for glycemias <100 mg/dL, and ±15 % for glycemias ≥100 mg/dL).
Glucose concentrations (mg/dL) in heparinized plasma in the Core Laboratory (method: glucose hexokinase, Atellica® Solution-CH; Siemens-Healthineers) Vs. glucose concentrations in heparinized whole blood as measured on POCT glucometers.
| Hematocrit, % | Glucose, mg/dL mean (CV%) | ||
|---|---|---|---|
| (range) | Core lab | Gluc-A | Gluc-B |
| 20–25 | 48 (2.1) | 55 (1.9) | 50 (2.2) |
| 20–25 | 125 (1.2) | 156 (1.3) | 130 (1.2) |
| 20–25 | 241 (1.5) | 265 (1.8) | 250 (1.7) |
| 41–45 | 48 (2.1) | 50 (1.9) | 49 (2.2) |
| 41–45 | 125 (1.2) | 127 (1.3) | 127 (1.2) |
| 41–45 | 241 (1.5) | 238 (1.8) | 240 (1.7) |
| 54–61 | 48 (2.1) | 45 (1.9) | 47 (2.2) |
| 54–61 | 125 (1.2) | 102 (1.3) | 120 (1.2) |
| 54–61 | 241 (1.5) | 220 (1.8) | 237 (1.7) |
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Gluc-A: glucometer not adjusting the result to the actual hematocrit – Freestyle Optium Neo (Abbott, Lake, IL, USA); electrochemical method, Glucose Dehydrogenase. Gluc-B: glucometer adjusting the result to the actual hematocrit – Nova StatStrip (Nova-Biomedical, Waltham, USA); electrochemical method, Glucose Oxidase. CV, analytical variability with respect to the mean value.
We agree with the authors that improvements in glucometers, both in analytical capabilities and in connectivity to electronic health records and full traceability, will increase their role in certain healthcare processes, reducing diagnostic and treatment delays, as well as analytical and clinical costs.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The authors state no conflict of interest.
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Research funding: None declared.
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Data availability: Not applicable.
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Article Note: The original article can be found here: https://doi.org/10.1515/almed-2024-0108.
References
1. Fabre-Estremera, B, Martínez-Chávez, E, Manzano Ocaña, M, Carcavilla Urquí, A, Morales Sánchez, MDLÁ, Pinilla Tejado, I, et al.. Uso de glucómetros durante la prueba de tolerancia oral a la glucosa en niños para el diagnóstico de prediabetes y diabetes. Estudio comparativo. Adv Lab Med/Avances en Medicina de Laboratorio 2024;5:197–204. https://doi.org/10.1515/almed-2024-0017.Search in Google Scholar PubMed PubMed Central
2. Sacks, DB, Arnold, M, Bakris, GL, Bruns, DE, Horvath, AR, Lernmark, Å, et al.. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Clin Chem 2023;69:808–68. https://doi.org/10.1093/clinchem/hvad080.Search in Google Scholar PubMed
3. Solnica, B, Skupień, J, Kuśnierz-Cabala, B, Słowińska-Solnica, K, Witek, P, Cempa, A, et al.. The effect of hematocrit on the results of measurements using glucose meters based on different techniques. Clin Chem Lab Med 2012;50:361–5. https://doi.org/10.1515/cclm.2011.770.Search in Google Scholar
4. Wada, Y, Nakamura, T, Kaneshige, M, Takahashi, S, Fujinaga, H, Tsukamoto, K, et al.. Evaluation of two glucose meters and interference corrections for screening neonatal hypoglycemia. Pediatr Int 2015;57:603–7. https://doi.org/10.1111/ped.12543.Search in Google Scholar PubMed
5. Demircik, F, Ramljak, S, Hermanns, I, Pfützner, A, Pfützner, A. Evaluation of hematocrit interference with MyStar extra and seven competitive devices. J Diabetes Sci Technol 2015;9:262–7. https://doi.org/10.1177/1932296814565790.Search in Google Scholar PubMed PubMed Central
6. FDA. Blood glucose monitoring test systems for prescription point-of-care use: guidance for industry and food and drug administration staff. U.S. Department of Health and Human Services; 2020. Recuperado de: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/content-premarket-submissions-device-software-functions.Search in Google Scholar
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© 2024 the author(s), published by De Gruyter, Berlin/Boston
This work is licensed under the Creative Commons Attribution 4.0 International License.
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- Reply to: “Considerations about the use of glucometers for testing glucose tolerance”
- Respuesta a la carta al editor: “Consideraciones acerca del uso de glucómetros durante la prueba de tolerancia oral a la glucosa” (https://doi.org/10.1515/almed-2024-0108)
Articles in the same Issue
- Frontmatter
- Editorial
- Lights and shadows of artificial intelligence in laboratory medicine
- Luces y sombras de la inteligencia artificial en la medicina de laboratorio
- Review / Artículo de Revisión
- Fundamentals of lipoprotein(a) request and quantification in the clinical laboratory
- Aspectos fundamentales en la solicitud y determinación de la lipoproteína(a) en el laboratorio clínico
- Original Article / Artículo Original
- Evaluating seven bioinformatics platforms for tertiary analysis of genomic data from whole exome sequencing in a pilot group of patients
- Evaluación de siete programas bioinformáticos para el análisis terciario de datos genómicos generados a partir de la secuenciación del exoma completo en un grupo piloto de pacientes
- Parameters of glycemic variability in continuous glucose monitoring as predictors of diabetes: a prospective evaluation in a non-diabetic general population
- Parámetros de variabilidad glucémica de la monitorización continua de glucosa como predictores de diabetes: evaluación prospectiva en una población general sin diabetes
- Reference intervals of hematological parameters in the Chilean adult population and the Mapuche ethnic group
- Intervalos de referencia de parámetros hematológicos en población chilena adulta y en la etnia mapuche
- Lipid metabolism in overweight/obese children vs. normal weight children in a north-eastern region of Spain
- Estudio del metabolismo lipídico en niños aragoneses con sobrepeso/obesidad vs. niños normopeso
- Short Communication / Comunicación Breve
- Evaluating the research parameters available on the Sysmex® XN-series hematology analyzers as markers of dysplasia in peripheral blood
- Valoración de los parámetros de investigación de los analizadores hematológicos de la serie XN (Sysmex®) como marcadores de displasia en sangre perifèrica
- Evaluation of an alternative centrifugation protocol for reducing total turnaround time
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- Case Report / Caso Clínico
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- Consideraciones acerca del uso de glucómetros durante la prueba de tolerancia oral a la glucosa
- Reply to: “Considerations about the use of glucometers for testing glucose tolerance”
- Respuesta a la carta al editor: “Consideraciones acerca del uso de glucómetros durante la prueba de tolerancia oral a la glucosa” (https://doi.org/10.1515/almed-2024-0108)
