SLR - September 2018 - Nathaniel George

Investigation of the Accuracy of 18 Marketed Blood Glucose Monitors

Reference: David C. Klonoff, Joan Lee Parkes, Boris P. Kovatchev, David Kerr, Wendy C.Bevier, Ronald L. Brazg, Mark Christiansen, Timothy S. Bailey, James H. Nichols,Michael A. Kohn. Investigation of the Accuracy of 18 Marketed Blood Glucose Monitors. Diabetes Care. Aug 2018, 41 (8) 1681–1688.

Scientific Literature Review

Reviewed By: Nathaniel George, DPM
Residency Program: St. Vincent Hospital, Worcester, MA

Podiatric Relevance: High glucose levels have been directly linked to chronic nonhealing ulcerations. Podiatric physicians have the responsibility of treating these type of ulcerations. Higher levels of blood glucose can damage the nerve endings in many areas of the body and organs, which is why tight blood glucose control is an essential aspect of diabetes care. Many people with diabetes are entirely unaware of the importance of maintaining lower blood glucose levels. The study reviews the use of 18 systems that have been cleared by U.S. Food and Drug Administration on 115 subjects. The goal of this study was to measure the accuracy of commercially used blood glucose monitor systems. The podiatric interest in this article is the fact that all glucose monitors are not created equal, and knowing which brands have accurate measurements can help to maintain normal blood glucose levels, which in turn helps in treating chronic ulcerations.

Methods: The study was approved by the Schulman Institutional Review Board, and all subjects gave informed consent prior to participating in the study. A blood glucose monitor (BGM) was tested on 115 subjects to have a capillary blood glucose (BG) level measured on six different systems and a reference capillary sample prepared for plasma testing at a reference laboratory. Products were obtained from consumer outlets and tested in three triple-blinded studies. A compliant BG result was defined as within 15 percent of a reference plasma value or within 15 mg/dL. The proportion of compliant readings in each study was compared against a predetermined accuracy standard using the modified Bland-Altman analysis and Surveillance Error Grid (SEG). The SEG is based on risk assessments of BGM errors by diabetes clinicians that assign a unique risk score to each system-measured data point when compared with a reference value.

Results: The different accuracy metrics produced almost identical BGM rankings. Six of the 18 systems had greater than 97 percent of readings in the “no risk” category in all three studies, five systems met it in two studies and three met it in one study. Four BGMs did not meet the accuracy standard in any of the three studies.

Conclusions: The BGMs that are commercially produced demonstrated many shortcomings. Only six of the 18 commercially available BGMs met a predefined accuracy standard on three out of three studies of 97 percent accurate. This is important to consider that BGMs do not always meet the level of analytical accuracy currently required for regulatory clearance. The information obtained will assist patients, professionals and payers in choosing products. It is important to reinforce in patients that affordable products are not always accurate, which will result in irregular blood glucose levels in the end.

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