What is all the buzz about use of glucose meters in critically ill patients? Glucose meters have been used for more than 30 years to provide rapid measurement of glucose on whole blood fingersticks from patients with diabetes. Originally developed for patient self-testing, glucose meter use has expanded throughout the healthcare industry. Meters currently are being used in physician offices, schools, nursing homes, ambulances, helicopters, airplanes, and cruise ships. Glucose meters have even traveled on the Space Shuttle! They are common throughout hospitals and are used for a variety of reasons, from quick checks of glucose levels to hourly glucose level monitoring as part of intensive insulin protocols.
So, why is there now a concern over the use of glucose meters? Problems with glucose meters have been known from the start. Glucose meters designed for patient self-monitoring are validated primarily on ambulant, well patients who happen to have diabetes. These meters are calibrated for normal hematocrits and physiology. Study data from patient self-management is how many of the current meters gained market approval through the Food and Drug Administration (FDA). Unfortunately, when the same meters and test strip methodologies are applied to sick inpatients, comparable performance to outpatient use is not always achieved. Hospitalized patients pre-
sent with extremes of hematocrit, pH, and perfusion that challenge glucose meter performance. They also often are on intravenous drug and oxygen therapies that pose potential for interferences not found in patient self-management. Recent incidents with maltose interference and a specific glucose meter methodology led to death in several hospitalized patients.
These concerns caused FDA to respond in two ways: 1) to add a sentence to the limitations section of all glucose meter package inserts that meters have not been evaluated in critically ill patients; and 2) to release, in January 2014, draft guidance on Blood Glucose Monitoring Test Systems for Prescription Point-of-Care Use. The latter describes the studies that FDA recommends for manufacturers who intend to submit premarket notifications (510k) for blood glucose meters. Although FDA’s guidance was directed at glucose meter manufacturers, the New York State Department of Health responded almost immediately with a letter to laboratories warning about off-label use of glucose meters. Examples of off-label use mentioned in this letter include monitoring glycemic control in hospitalized non-diabetic patients; use on critically ill patients; and use in health fairs and other community events to screen the public for diabetes. Off-label use would default the CLIA-waived meter to CLIA high-complexity and require laboratories to validate the full analytical and clinical performance of the device in the critically ill population. Until such requirements are met, the state warned that use of glucose meters at health fairs, other community screening events, and/or in critical care settings should be discontinued.
The Centers for Medicare and Medicaid Services (CMS) issued a similar warning in a Survey and Certification letter released last November. According to this document, use of a test outside of its intended FDA-approved/cleared use, limitations, or precautions, as indicated in the manufacturer’s instructions, would be considered off-label use and default the test to CLIA high-complexity. With any non-compliance identified, surveyors would issue a written statement of deficiency and require follow-up according to applicable regulations and guidance. However, in a follow-up communication dated March 13, CMS temporarily withdrew the aforementioned Survey and Certification letter, reissued it as a draft with draft clarifications, and requested comments on the draft guidance. This communique puts a temporary hold on surveyors citing deficiencies pending resolution of
What does this mean for clinical laboratories and hospitals currently using glucose meters? Laboratories have responded to these developments in a variety of ways, from stopping glucose testing in intensive care units altogether to taking no action and adopting a “wait-and-see” approach. What all this discussion has done is raise awareness about the limitations of point-of-care testing (POCT) devices generally, and glucose meters in particular. No device is fool-proof, and every test has limitations. As laboratory directors, POC coordinators, and operators of POCT devices, we all need to be aware of a device’s limitations and avoid use under off-label situations. Limitations from the manufacturer’s package insert should be part of our policies, procedures, and training materials. There is a lot of ongoing debate over the FDA-imposed limitation of use in critically ill patients with newer glucose meters, as there is no consensus over the definition of “critically ill.” CMS and FDA are not defining this term, and leave that to the individual institution.
What are we to make of all of this? Do hospitals have to stop bedside testing with glucose meters, and if so, what are the alternatives?
At this time staff can continue to use glucose meters, provided they stay within the package insert recommendations. Alternatively, hospitals can limit glucose testing to non-critical patients and use blood gas analyzers or send samples to the central lab for critically ill patients.
Labs also should talk to their clinicians, define the “critically ill” population for their specific meter and institution, and ensure use within each manufacturer’s recommendations. CMS has noted that further clarification is forthcoming, but until then, labs should ensure that their actions, by either continuing to use the meters or discontinuing use, first and foremost do not harm patients.
James H. Nichols, PhD, DABCC, FACB, is a professor of pathology, microbiology, and immunology, associate medical director for clinical operations, and medical director of clinical chemistry at Vanderbilt University School of Medicine in Nashville, Tennessee. He also chairs AACC’s Government Relations Committee.
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