FDA Warnings about Blood Glucose Monitoring Devices

Blood glucose monitoring devices can be used in the home or in health care settings. They are frequently used by patients with diabetes to guide treatment, such as to determine the best insulin dose. Recent Food and Drug Administration (FDA) warnings about glucose monitors have highlighted the dangerous risks that may emerge when these devices malfunction.

At-home glucose monitoring takes two forms: periodic (several times per day) capillary glucose monitoring, in which blood is obtained through finger pricks, and continuous glucose monitoring, achieved using newer wearable technologies.[1],[2] The finger prick method involves placing a drop of blood on a test strip that is inserted into a reading device. By contrast, continuous glucose monitoring involves a sensor that pierces the skin and indirectly measures blood glucose levels by measuring levels in the interstitial fluid (the fluid that surrounds the cells just below the skin surface). If working properly, both methods produce similar results, although continuous glucose monitoring results may be delayed 10 to 15 minutes, may be lower in magnitude, and may be less accurate at very high and very low glucose levels. Additionally, acetaminophen (TYLENOL and generics) and high-dose vitamin C, among other drugs, may falsely elevate continuous glucose monitoring readings on some devices.

Blood glucose monitoring

Daily glucose monitoring is commonly used by people taking insulin or other medications that can cause hypoglycemia.[3]

People with type 1 diabetes commonly use either periodic or continuous glucose monitoring to optimize insulin dosing and make dietary adjustments. If continuous glucose monitoring is not used, periodic monitoring is recommended at least four times per day: before each meal and at bedtime.

For people with type 2 diabetes, glucose monitoring is encouraged if they are taking insulin. Glucose monitoring may also help people taking sulfonylureas, such as glimepiride (generics). Although less commonly necessary for people with type 2 diabetes treated with other medications or diet alone, glucose monitoring may be recommended when treatment changes are made.[4],[5],[6],[7]

Recent FDA warnings

In December 2025, the FDA issued an “early alert” advising people to stop using sensors (skin probes) for the FreeStyle Libre 3 continuous glucose monitoring system, manufactured by Abbott Diabetes Care.[8],[9] This followed a company report that a production lot of approximately 3 million sensors was linked to seven deaths and 736 injuries worldwide. In the United States, 57 injuries and no deaths were reported. The concern was that these sensors might yield falsely low glucose measurements, thereby encouraging patients using the device to reduce or delay insulin doses or increase carbohydrate intake, both of which can cause hyperglycemia.

By early February 2026, this warning intensified to a Class I recall, the most serious of the FDA’s three recall classifications, and reported injuries increased to 860 worldwide. Both the FDA and the company issued communications, including letters to suppliers, doctors and patients, advising them to stop using these sensors and seek replacements. Unique identification numbers for the recalled devices, which include both FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors, are available on the websites of Abbott Diabetes Care as well as the FDA. The identification numbers also appear on device packaging and can be accessed by scanning sensors with a smartphone application (app).

Also in February 2026, the FDA issued an “early alert” that Trividia Health, Inc., manufacturer of another blood glucose monitoring system, was updating the product’s label because of a potentially confusing error message, “E-5,” sometimes displayed by the devices.[10] The affected devices included TRUE METRIX, TRUE METRIX AIR, TRUE METRIX GO and TRUE METRIX PRO. Misinterpretation of this error message has been linked to 114 injuries and one death. The new labeling says that the “E-5” message reflects either a “test strip error” or “very high blood glucose.” It further warns the user that if “E-5” appears, a retest should be performed with a new strip. Additionally, the new label states that “[i]f the error persists and you have symptoms such as fatigue, excess urination, thirst, or blurry vision, seek medical attention immediately.” These symptoms suggest that hyperglycemia may be present when the “E-5” error message appears.

In response to these problems with the continuous glucose monitors from Abbott Diabetes Care, clinicians have reminded patients to keep extra glucose monitoring supplies available and to be prepared for sensor failures.[11] For example, Dexcom, the manufacturer of another continuous glucose monitor, the Dexcom G7 15 Day, cautions users that 26% of their sensors fail to last the advertised 15 days.[12]

What You Can Do

Continuous glucose monitoring may help many patients with diabetes, especially those on insulin, manage their treatment. However, blood monitoring may also need to be used periodically, and both monitoring systems can fail. If you have type 1 or type 2 diabetes and are using a home glucose monitoring system, discuss with your clinician which approach is best for you and make sure you are promptly informed of any recalls.

Be aware of early signs of hyperglycemia, such as increased thirst or hunger, frequent urination, headache and blurred vision.[13] Also be aware of the many symptoms of hypoglycemia, such as paleness, shakiness, sweating, headache, hunger or nausea, irregular heartbeat, fatigue, irritability or anxiety, difficulty concentrating, lightheadedness and tingling or numbness of the lips, tongue or cheeks.[14]
 

References

[1] Weinstock RS. Glucose monitoring in the ambulatory management of nonpregnant adults with diabetes mellitus. UpToDate. August 26, 2024.

[2] Kurul F, Aydogan D, Janat S. Wearable sensors for health monitoring: current appplications, trends, and future directions. Biosensors and Bioelectroics: X. 2026 March; 28:100727.

[3] Weinstock RS. Glucose monitoring in the ambulatory management of nonpregnant adults with diabetes mellitus. UpToDate. August 26, 2024.

[4] Ibid.

[5] Malanda UL, Welschen LM, Riphagen II, et al. Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin. Cochrane Database Syst Rev. 2012 Jan 18;1(1):CD005060.

[6] Machry RV, Rados DV, Gregório GR, Rodrigues TC. Self-monitoring blood glucose improves glycemic control in type 2 diabetes without intensive treatment: A systematic review and meta-analysis. Diabetes Res Clin Pract. 2018;142:173-187.

[7] Young LA, Buse JB, Weaver MA, et al.; Monitor Trial Group. Glucose self-monitoring in non-insulin-treated patients with type 2 diabetes in primary care settings: a randomized trial. JAMA Intern Med. 2017 1;177(7):920-929.

[8] Aleccia J. Faulty glucose monitors linked to 7 deaths and more than 700 injuries, FDA warns. Associated Press. December 4, 2025. https://apnews.com/article/abbott-freestyle-libre-glucose-monitor-sensor-warning-a7850dc6a08a189fde3311175490123f. Accessed March 6, 2026.

[9] U.S. Food and Drug Administration. Glucose monitor sensor recall: Abbott Diabetes Care removes certain FreeStyle Libre 3 and FreeStyle Libre 3 Plus sensors. February 5, 2026. https://www.fda.gov/medical-devices/medical-device-recalls-and-early-alerts/glucose-monitor-sensor-recall-abbott-diabetes-care-removes-certain-freestyle-libre-3-and-freestyle.   Accessed March 4, 2026.

[10] U.S. Food and Drug Administration. Early alert: Trividia health issues correction for TRUE METRIX blood glucose monitoring systems. February 17, 2026. https://www.fda.gov/medical-devices/medical-device-recalls-and-early-alerts/early-alert-trividia-health-issues-correction-true-metrix-blood-glucose-monitoring-systems?utm_medium=email&utm_source=govdelivery. Accessed March 11, 2026.

[11] Peters AL. Clinical concerns: insulin delivery systems. Medscape. January 9, 2026. https://www.medscape.com/viewarticle/clinical-concerns-insulin-delivery-system-sensors-2026a10000co. Accessed January 9March 6, 2026.

[12] Dexcom. FAQs. “How long does the Dexcom G17 15 Day sensor last?” https://provider.dexcom.com/support/faqs.  Accessed March 20, 2026.

[13] Cleveland Clinic. Hyperglycemia (High Blood Sugar). March 2, 2023. https://my.clevelandclinic.org/health/diseases/9815-hyperglycemia-high-blood-sugar. Accessed March 6, 2026.

[14] Mayo Clinic. Hypoglycemia. November 18, 2023. https://www.mayoclinic.org/diseases-conditions/hypoglycemia/symptoms-causes/syc-20373685. Accessed March 11, 2026.