The FreeStyle Libre Continuous Glucose Monitor

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The FreeStyle Libre system is a continuous glucose monitor (CGM) worn on the upper arm that provides real-time blood glucose (blood sugar) readings every minute for people who have type 1 diabetes or type 2 diabetes, especially those who take insulin. It comes in two options: The original Freestyle Libre 14-day system is approved for adults 18 and older and the Freestyle Libre 2 system is approved for adults and children ages 4 and older.

It has been reported that people who frequently test their blood sugar have lower A1C levels (a measure of average glucose levels over two to three months) and steadier glucose levels.

Woman showing her continous glucose monitor
Jeff Spicer / Springer / Getty Images 

However, traditional monitoring can be intensive and invasive and requires multiple fingersticks to draw and test blood each day. CGM devices like the FreeStyle Libre can greatly simplify this process.

How It Works

The FreeStyle Libre system uses modern technology to provide real-time glucose readings every minute with a pre-calibrated sensor. These devices, two among several in a newer generation of CGMs, don't have the bulky transmitter of CGMs past. Instead, they use a small, water-resistant sensor inserted just under the skin on the back of the arm where they measure interstitial fluid, which is comparable to capillary blood.

Timing and Duration

After a one-hour startup period, you can retrieve a blood glucose reading instantly by scanning the sensor with your reader or smartphone app. (As of March 2021, the FDA was still reviewing the app for the Freestyle Libre 2, so the reader is still needed for that model.) You can scan as often as you'd like, but in order to capture all data, it is recommended that you scan your sensor at least once every eight hours to record 100% of the data.

Studies conducted by Abbott, the maker of the FreeStyle Libre, have demonstrated that people who use this sensor wind up scanning the sensor more often than they would test their blood sugar with a fingerstick, which provides them with more accurate data.

The Libre can store 90 days' worth of data and can be worn for up to 14 days, at which point it stops working and must be replaced. Once you are finished with your sensor, you can dispose of it.

When Manual Testing May Be Necessary

The Libre's reader also has a blood glucose meter within the system. This can allow you to double check that the CGM is accurate. Inaccuracies sometimes occur with CGMs during rapid changes in blood glucose, such as after eating, dosing insulin, or exercising. Severe dehydration and excessive water loss may also cause inaccurate results. During these times, you'll need to confirm your blood sugar level with a fingerstick.

The FreeStyle Libre also will alert you if for some reason it isn't able to determine where your glucose is trending by displaying a warning symbol. Whenever you see this symbol, you should do a finger prick blood glucose test.

The FreeStyle Libre 2 has alarms to alert you if your glucose levels are too high or two low, but you need to turn them on and your reader needs to be within 20 feet of you in order to receive them.

The original FreeStyle Libra 14 day is not designed to let the wearer know if their glucose levels are too high or too low. If you begin having symptoms of either condition, check your blood sugar manually.

Cost

For people who have private insurance or are on Medicaid, the FreeStyle Libre may cost $40 to $75 per month. The device is fully covered by Medicare for those who qualify. It is available in pharmacies nationnwide; your doctor can help you locate one. Download the buying guide from the FreeStyle Libre website to find a list of providers.

In addition to the cost of the device, the FreeStyle Libre uses test strips called Precision Neo test strips. Typically, a box of 50 costs about $20. They are individually foil-wrapped so that they can be used until the expiration date. Using other test strips with the built-in meter may produce an error or cause it to not turn on or start a test. You cannot use the meter to test for ketones.

Benefits

The FreeStyle Libre CGM eliminates fingersticks for calibration, which translates into less manual effort. Instead of checking finger sticks multiple times per day, people with diabetes can scan their CGM (a painless procedure) to get real-time glucose readings to use for insulin dosing, meal planning, etc.

For those who loathe testing, this could help them to better manage their diabetes, In addition, large amounts of data and trend reports can help people with diabetes reduce their risk for low blood sugar and help them to figure out insulin dosing and meal planning.

Comparison to Other Devices

The Libre device is referred to as a flash glucose monitoring system. As compared to other CGMs, like the Dexcom G6, the Libre system checks glucose every minute rather than every five minutes and it can be worn for 14 days as opposed to 10. It is very accurate and does not require fingerstick calibrations. Because the Libre does not require a transmitter, the price for it and its sensors is lower compared to other CGMs.

Additionally, sensor placement is not approved for sites other than the back of the arm (other CGMs are approved for belly and buttocks placement). If placed in other areas, the sensor may not function properly.

Caveats

The original FreeStyle Libre 14 day does not feature automatic alarms to alert the wearer of too-high or too-low blood glucose levels. However, if after scanning your levels are abnormal, the reader will alert you and prompt you to set a reminder to scan again. Be aware the FreeStyle Libre has not been evaluated for use by people with hypoglycemia unawareness (meaning they are unable to recognize the symptoms of a extreme dip in blood sugar levels).

Storage

Storage is important for protecting the sensor and keeping the readings as accurate as possible. The FreeStyle Libre 14-day kit should be stored at a temperature between 39 degrees F (3.8 degrees C) and 77 degrees F (25 degrees C). The FreeStyle Libre 2 kit should be stored at a temperature between 36 degrees F (2.2 degrees C) and 82 degrees F (27.7 C). Both Libre devices should be kept at a non-condensing humidity of between 10% and 90%. It your refrigerator meets these criteria you can certainly store the kit there.

A Word From Verywell

The FreeStyle Libre Glucose Monitoring System eliminates the need for fingerstick calibration, which is exciting news for people with diabetes.

Your age and your interest in features, such as alarms or the use of a smartphone app, can help you and your doctor determine which FreeStyle Libra device may work best for you. Eligible patients with diabetes must receive a prescription to get this meter. If you think you are eligible and are interested, ask your healthcare team about it. If you have any doubts, you can always see if you can trial the FreeStyle Libre before getting started.

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Article Sources
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  2. Blum A. Freestyle Libre glucose monitoring system. Clin Diabetes. 2018;36(2):203-204. doi:10.2337/cd17-0130

  3. Abbott Laboratories. FreeStyle Libre.

  4. Abbott. FreeStyle Libre 14 Day indications and important safety information. February 2021.

  5. Abbott. FreeStyle Libre products. Updated February 2021.

  6. Centers for Medicare & Medicaid Services. Therapeutic continuous glucose monitors.

  7. Abbott. FreeStyle Libre: Medicare guide. Updated November 2020.

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