Flash Glucose Monitoring

Continuously measures glucose levels throughout the day

Designed to replace the need for routine finger pricks for people with diabetes, a flash glucose monitoring system is made up of a sensor that is worn on the back of the upper arm that continuously measures the glucose concentration in the body's interstitial fluid.
Using the Reader or a mobile app people with diabetes ages 4 and olderѰ, including pregnant women, can scan their sensor to see their glucose levels.

What’s the difference between flash glucose monitoring
and blood glucose monitoring?

Sensor glucose readings come from the interstitial fluid,
a thin layer of fluid that surrounds the cells of the tissue below the skin4 and not from the blood.

Monitoring diagram

Interstitial fluid readings and blood glucose readings don’t always match

Glucose in the blood takes time to make its way into the interstitial fluid so there may be a lag time. The average lag time between Sensor and blood glucose readings is about 2.4 ± 4.6 minutes for adults and 2.1 ± 5.0 minutes for children.5

When glucose levels are stable, the two readings may be very similar. However, if glucose is rising or falling, then they might be different.6


When blood glucose levels are stable, the glucose measurement displayed by the FreeStyle Libre system in the interstitial fluid, is similar to blood glucose.


When blood glucose levels increase, the glucose measurement displayed by the FreeStyle Libre system in the interstitial fluid may be below the blood glucose reading.


When blood glucose levels decrease, the glucose measurement displayed by the FreeStyle Libre system in the interstitial fluid may be higher than the blood glucose reading.


The FreeStyle Libre System

The FreeStyle Libre system is the leading sensor glucose monitoring device globally7 and the only flash glucose monitoring system. It consists of a small, discreet Sensor worn on the back of the upper arm with a Reader or phone app to scan the Sensor. People with diabetes must scan once every 8 hours for a complete glycaemic picture, ensuring users remain engaged with their glucose monitoring throughout the day.

Note: Patients can scan their sensor with both the FreeStyle Libre reader and FreeStyle LibreLink on a compatible device. To use both, patients should start their sensor with the reader first then scan with their phone.

How accurate is the FreeStyle Libre System?

The FreeStyle Libre system is clinically proven to be accurate and consistent over 14 days5, without the need for finger prick calibration.​ ​In a study comparing the accuracy of the FreeStyle Libre system to other blood glucose referencing systems5 in adults, 99.9% of FreeStyle Libre sensor results were in the clinically acceptable zones A&B of the Consensus Error Grid with a MARD 9.2% over 14 days.

Note: All the values vs.Yellow Springs Instruments(YSI)
MARD= Mean Absolute Relative Difference

No finger prick calibration ever

Calibration is needed for commercially available CGM systems because the sensitivity of each sensor can vary within each batch that is made. The FreeStyle Libre flash glucose monitoring sensor is calibrated at the factory - so people using it won’t need to calibrate it using a finger prick, ever. This means users can be confident in the accuracy of the system, and you can be confident the accuracy patients are receiving is what is reported, without being affected by discrepancies caused by finger prick calibration.

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