Why Sensor-Based Glucose

Sensor-based glucose monitoring system continuously measures glucose levels throughout the day without the need for finger pricks

Designed to replace the need for routine finger pricks, a sensor based 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 up to 14 days.

Using the FreeStyle LibreLink app, patients can scan their FreeStyle Libre sensor to see their glucose levels.

Sensor-Based Glucose Monitoring vs Blood Glucose Monitoring

What's the difference between sensor-based 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 skin and not from the blood.

Flash Glucose Monitoring Flash Glucose Monitoring

Interstitial Fluid and Blood Glucose Readings

Why don’t interstitial fluid readings and blood glucose readings always match?

Glucose in the blood takes time to make its way into the interstitial fluid so there may be a lag time between the readings.

Average lag time between the FreeStyle Libre sensors and blood glucose readings:

  • 2.1 minutes for children4
  • 2.4 minutes for adults4

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

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

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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.

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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.

Watch the video to find out more about the difference between testing interstitial fluid vs blood glucose


How accurate is sensor-based glucose monitoring?

The FreeStyle Libre sensor is accurate, stable and consistent over 14 days4 without the need for finger prick calibration.

Accuracy is assessed by looking at the glucose readings the sensor provides compared to known independent reference. In this case, the reference is a finger prick blood glucose reading which is taken at the same time as the sensor scan. The comparison between the two different readings is plotted on a graph called a Consensus Error grid.

The closer the sensor reading to the reference blood glucose meter reading, the better the accuracy. This is reflected by the Consensus Error Grid by various areas on the graph labelled A to E. The higher the percentage of readings in Zones A and B, the more accurate the sensor is. The consensus Error Grid below shows 99.9% of readings in Zone A + B of the Consensus Error Grid.4

accuracy accuracy accuracy

No finger prick calibration, ever4,†

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 sensor is calibrated at the factory – so your patients won’t need to calibrate it using a finger prick, ever. This means you and your patients can be confident in the accuracy of the system, and that the accuracy you're receiving is what is reported, without being affected by discrepancies caused by finger prick calibration.

Sensor based glucose monitoring products

FreeStyle Libre System shown on a smartphone. FreeStyle Libre System shown on a smartphone.

FreeStyle LibreLink App

The FreeStyle LibreLink allows patients to interpret their glucose data and help them make more informed diabetes management decisions based on your advice.

FreeStyle Libre System shown on a smartphone. FreeStyle Libre System shown on a smartphone.

FreeStyle Libre System

Our Flash Glucose Monitoring system


References & Disclaimers

Images are for illustrative purposes only. Not real patient or data.

† Finger pricks are required if glucose readings do not match symptoms or expectations.

◊ The FreeStyle LibreLink app and the FreeStyle Libre reader have similar but not identical features. Finger pricks are required if readings do not match symptoms or expectations. The FreeStyle Libre sensor communicates with the FreeStyle Libre reader that started it or the FreeStyle LibreLink app that started it. A sensor started by the FreeStyle Libre reader will also communicate with the FreeStyle LibreLink app. The FreeStyle LibreLink app is only compatible with certain mobile devices and operating systems. Please check the website for more information about device compatibility before using the app. Use of FreeStyle LibreLink requires registration with LibreView.

φ For a complete glycaemic picture, scan once every 8 hours.

₸ Sensor is water-resistant in up to 1 meter (3 feet) of water. Do not immerse longer than 30 minutes. Not to be used above 10,000 feet.

1. Hortensius, Johanna., et al. Perspectives of patients with type 1 or insulin-treated type 2 diabetes on self-monitoring of blood glucose: a qualitative study. BMC Public Health 12.1 (2012):167.

2. Chudyk, Anna., et al. Self-Monitoring Technologies for type 2 Diabetes and the Prevention of Cardiovascular Complications: Perspectives from End Users. Journal of Diabetes Science and Technology 5.2 (2011): 394–401.

3. Data on File, Abbott Diabetes Care. In a study conducted by Abbott Diabetes Care, 94% of patients surveyed (n=122) agree that the FreeStyle Libre sensor is comfortable to wear.

4. Alva S, et al. Accuracy of a 14-Day Factory-Calibrated Continuous Glucose Monitoring System With Advanced Algorithm in Pediatric and Adult Population With Diabetes. Journal of Diabetes Science and Technology. September 2020. doi:10.1177/1932296820958754.