Correspondence  |   May 2018
Assessing Glucose Meter Accuracy: The Details Matter!
Author Notes
  • Vanderbilt University Medical Center, Nashville, Tennessee (Y.L.).
  • (Accepted for publication January 31, 2018.)
    (Accepted for publication January 31, 2018.)×
Article Information
Correspondence   |   May 2018
Assessing Glucose Meter Accuracy: The Details Matter!
Anesthesiology 5 2018, Vol.128, 1044-1045. doi:10.1097/ALN.0000000000002149
Anesthesiology 5 2018, Vol.128, 1044-1045. doi:10.1097/ALN.0000000000002149
To the Editor:
We read with great interest the recent article by Dr. Karon et al. titled “Accuracy of Capillary and Arterial Whole Blood Glucose Measurements Using a Glucose Meter in Patients under General Anesthesia in the Operating Room.”1  We congratulate the authors on identifying a glucose meter potentially safe for insulin dosing in the perioperative environment using both capillary and arterial samples, given that no glucose meter is currently approved by the U.S. Food and Drug Administration for use with capillary (fingerstick) samples in critically ill patients.2  Using this meter may offer an important step toward improved blood glucose control in these patients. The authors attributed the improved accuracy of glucose measurement, at least partially, to the fact that the newer generation glucose meters can “correct for hematocrit or other interferences.” We have three comments.
First, the authors used blood gas analyzers as the reference method. Even though blood gas analyzers generally are considered more accurate than meters, they have never been established as a reference method in the literature. In clinical practice, the central laboratory device has been used as a reference method when assessing glucose meters because of its high accuracy.3,4  We are wondering why the authors used blood gas analyzers rather than central laboratory devices as the reference method, and how we can interpret the accuracy of glucose meters in this article if the reference method used is not the commonly used “clinical reference method.”
Second, the authors assessed the accuracy of glucose meters in a narrow range of values, which were between 70 and 250 mg/dl, with no hypoglycemic values studied. Multiple previous studies have shown that measurements by glucose meters are more accurate in the “normal physiologic” range rather than hypoglycemic or hyperglycemic values.5–7  Thus, we are wondering how the accuracy data of this meter in a range of relatively “physiologic” glucose values could be generalized to its accuracy in a wider range of glucose values that we are concerned about in the clinical practice.
Third, we agree with the authors that patients in the operating room share similarities with patients in the intensive care units. These two populations, however, also could be vastly different. For example, one of the biggest concerns with using glucose meters with capillary samples in “critically ill patients” was impaired peripheral perfusion.2  Although the majority of patients in this study received vasopressor treatment during their care, the dose of vasopressor was rather small and most likely just counteracted the vasodilatory effect of the anesthetics. It is difficult to determine if these patients had impaired or actually improved peripheral perfusion. These patients are very different from patients in the intensive care unit who are receiving high-dose vasopressors with other evidence of poor peripheral perfusion, such as lactatemia, acidosis, or peripheral edema. Therefore, we need to be cautious in extrapolating these results from the perioperative population to the intensive care unit population.
No doubt glucose management is an important part of standard patient care, but with the enormous amount of literature published every year regarding glucose measurement accuracy with various devices, readers should be very cautious about interpreting the results and careful before incorporating those results into their clinical practice. Many factors need to be considered when it comes to assessing device accuracy, including the reference method, range of glucose values tested, sample sources, assessment methodology, and patient populations. The details matter!
Competing Interests
The authors declare no competing interests.
Yafen Liang, M.D., Mark J. Rice, M.D. Vanderbilt University Medical Center, Nashville, Tennessee (Y.L.).
Karon, BS, Donato, LJ, Larsen, CM, Siebenaler, LK, Wells, AE, Wood-Wentz, CM, Shirk-Marienau, ME, Curry, TB Accuracy of capillary and arterial whole blood glucose measurements using a glucose meter in patients under general anesthesia in the operating room. Anesthesiology 2017; 127:466–74 [Article] [PubMed]
U.S. Food and Drug Administration: Blood glucose monitoring test system for prescription point-of-care use: Draft guidance for industry and food and drug administration staff. Draft guidance issued on January 7, 2014. Available at: Accessed May 7, 2016
Rebel, A, Rice, MA, Fahy, BG Accuracy of point-of-care glucose measurements. J Diabetes Sci Technol 2012; 6:396–411 [Article] [PubMed]
Burtis, CA, Ashwood, ER, Bruns, DE Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 2006, pp 4th ed. St. Louis, Missouri, Elsevier-Saunders, 868–71
Pereira, AJ, Corrêa, TD, de Almeida, FP, Deliberato, RO, Lobato, Mdos S, Akamine, N, Silva, E, Cavalcanti, AB Inaccuracy of venous point-of-care glucose measurements in critically ill patients: A cross-sectional study. PLoS One 2015; 10:e0129568 [Article] [PubMed]
Kanji, S, Buffie, J, Hutton, B, Bunting, PS, Singh, A, McDonald, K, Fergusson, D, McIntyre, LA, Hebert, PC Reliability of point-of-care testing for glucose measurement in critically ill adults. Crit Care Med 2005; 33:2778–85 [Article] [PubMed]
Schifman, RB, Nguyen, TT, Page, ST Reliability of point-of-care capillary blood glucose measurements in the critical value range. Arch Pathol Lab Med 2014; 138:962–6 [Article] [PubMed]