Freestyle Libre 2 Sensor

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Sep 25, 2023

Warnings

FreeStyle Libre 2 Risks, Warnings, and Complications

FreeStyle Libre 2 may cause serious health problems in some people. Talk to your healthcare professional about other methods of glucose monitoring if you are at an increased risk of complications from this system. Some of the risks of using FreeStyle Libre 2 include:

IMAGING TESTS: You should remove the FreeStyle Libre 2 sensor before imaging studies such as X-rays, MRI scans, CT scans, and heat treatments such as diathermy. Tell your healthcare providers and laboratory personnel you are using this device before any tests or procedures.
SECURITY SCANNERS: You should not go through body scanners or X-ray machines if you are wearing a CGM device such as FreeStyle Libre 2. Tell security personnel you are wearing a CGM system and request an alternate method of screening, such as a hand-wand wand, walk-through metal detector, or visual inspection.
MATCH SYMPTOMS: If you have symptoms of hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar) that do not match your FreeStyle Libre 2 readings, do a fingerstick blood sugar test and call your provider if the results are out of range. The FreeStyle Libre 2 reader has a built-in fingerstick glucose monitor. However, if you are using a smartphone app to track your glucose levels, then you will need a separate blood glucose monitor along with the FreeStyle Libre 2 kit.
REAL-TIME GLUCOSE ALARMS: Make sure the optional alarms in FreeStyle Libre 2 are turned on in the reader or app. Keep in mind that your smartphone or reader has to be no more than 20 feet away from you for the alarms to work. If you're using a smartphone device, check information about mobile devices and operating systems to confirm compatibility as well as appropriate settings (for example, ensure Bluetooth is turned on). Ensure the reader and smartphone are charged and switched on. If an alarm sounds, you will need to scan the sensor to get the glucose reading.
FALSE READINGS: Taking vitamin C supplements can give falsely high glucose levels, and taking aspirin can give falsely low glucose levels with FreeStyle Libre 2. Check with your healthcare provider before taking any supplements or medications.
SKIN IRRITATION: FreeStyle Libre 2 sensors are attached to your skin with an adhesive, which can cause skin irritation. Remove the sensor and contact your healthcare provider if you develop redness, swelling, or irritation in the area of application.
SINGLE-USE SENSORS: FreeStyle Libre 2 sensors are for single use only and stop working automatically after 14 days. Do not use a sensor for more than 14 days, do not reuse it, and do not use someone else’s sensors. This can result in inaccurate readings and put you at risk of infections. If a sensor comes loose, remove it and replace it with a new one.

Precautions Before Starting FreeStyle Libre 2

Tell your doctor if you have had allergic reactions to CGM devices in the past.

Give your doctor or pharmacist a complete list of your current medications, including prescription drugs, nonprescription drugs, vitamins, supplements, and herbal remedies. This can help avoid possible interactions and inaccurate glucose readings from FreeStyle Libre 2. Be sure to tell your provider if you take vitamin C supplements or aspirin, as they can interfere with the readings provided by this device.

Give your doctor a complete medical history. FreeStyle Libre 2 may not be right for everyone, for example, pregnant women, critically ill patients, children below 4 years of age, people on dialysis, and those with other implantable devices like cardiac pacemakers.

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy in the near future, or are breastfeeding.

Check information about device compatibility before using the system in conjunction with a smartphone app. The app is only compatible with certain mobile devices. Use of the FreeStyle Libre 2 app requires registration with LibreView.

Precautions During Use of FreeStyle Libre 2

Keep all your medical and lab appointments while using FreeStyle Libre 2. Continue taking your diabetes medications as prescribed. Do not ignore any symptoms that could be due to high or low blood sugar. If your symptoms do not match the readings from FreeStyle Libre 2, check your glucose level with a fingerstick blood glucose meter and call your doctor.

Use sensors and applicators from the same package to ensure accurate readings. Apply the sensor to clean dry skin at the back of your upper arm. This system will not work properly if it is applied anywhere else on the body. Use a slightly different area of skin at the back of your upper arm every time you apply a new sensor to prevent irritation. Avoid applying the sensor over lumps, bumps, moles, scars, or stretch marks. Place the sensor at least 1 inch away from an insulin injection site.

Replace the sensor every 14 days. This is a single-use sensor - do not reuse it. Scan the sensor at least once every 8 hours. Less frequent scanning can lead to reduced performance. If the sensor comes loose, for example, due to sweating from intense exercise, remove it and replace it with a new one. Call your healthcare provider if you develop significant skin irritation at the site of the sensor application. If the sensor breaks during application or removal, contact your healthcare provider.

Do not use a FreeStyle Libre 2 kit that appears damaged or comes in an already opened package - this can put you at risk of infection, electrical shock, and other complications. Do not use sensors that are past their expiry date.

Tell all laboratory personnel that you are using the FreeStyle Libre 2 CGM system before X-rays, MRI scans, CT scans, or any medical tests or treatments.

Stay well hydrated, as dehydration can result in inaccurate readings.

Tell your doctor if you become pregnant while using FreeStyle Libre 2.

FreeStyle Libre 2 Drug Interactions

Taking certain medications while using FreeStyle Libre 2 can affect how the device works. Possible interactions may result in inaccurate blood glucose readings. Your doctor may change the dose of your medications, switch you to another medication, or monitor you carefully if there are known interactions between FreeStyle Libre 2 and your medicines.

FreeStyle Libre 2 may have potential drug interactions with the following medications:

Aspirin
Vitamin C supplements
Methyldopa
Tolbutamide

Give your healthcare professional a complete list of all the medications you are taking, including prescription drugs, non-prescription medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription and over-the-counter medicines or medical devices.

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