Freestyle Libre as a CGM with alarms: a do-it-yourself solution

A new do-it-yourself solution makes Abbott’s Freestyle Libre work as a continuous glucose monitor (CGM), with alarms if glucose goes too high or too low.

Out of the box, Freestyle Libre is not made for continuous glucose monitoring. Libre is marketed as “flash glucose monitoring” which helps to overcome “alarm fatigue”, one of the complaints of CGM users. Libre is built with NFC (“Near field communication”) — the technology which is often used in contactless payments, such as ApplePay. This means that the user needs to manually slide the device past the sensor to receive the latest reading.

NightScout Italy and DeeBee.it NGO solved the problem in a creative way:

  • an Android phone which supports NFC;
  • a sports armband to place the phone over the sensor;
  • an experimental app which makes the phone vibrate every five minutes to get the latest glucose value from the sensor.
A sports armband with an Android phone to read glucose values from Freestyle Libre.
A sports armband with an Android phone to read glucose values from Freestyle Libre.

The experimental app is an extension of Glimp, an unofficial app which is designed to replace FreeStyle Libre’s reader and has been available in Google Play Store for the past few months. Glimp reads glucose values directly from the sensor without using the predictive algorithm of Abbott, so the values are slightly different.

Comparison: (1) the original Abbott’s Freestyle Libre reader, (2) the unofficial Glimp app, and (3) a classic blood glucose meter. The experiment was made by a person with no diabetes.
Comparison: (1) the original Abbott’s Freestyle Libre reader, (2) the unofficial Glimp app, and (3) a classic blood glucose meter. The experiment was made by a person with no diabetes.

The new “CGM” app is available for download at Deebee.it (the button “Scarica” towards the end of the article). The solution is largely experimental and has its limitations:

  • Smartphone’s screen should be turned on and unlocked at all times; NFC wouldn’t work otherwise.
  • Battery life is 2-8 hours depending on the phone. Turning off Wifi and GPS may extend battery life.
  • The phone may heat up a lot.

This system can be useful to monitor aerobic and anaerobic exercise. Here is a high-tech setup which includes using two Android phones and two smartwatches:

An experimental Glimp setup for Freestyle Libre. With existing do-it-yourself solutions, Android smartphones and smartwatches can display the data from Libre.
An experimental Glimp setup for Freestyle Libre. With existing do-it-yourself solutions, Android smartphones and smartwatches can display the data from Libre.

Nightscout Italy has a lot of ideas for the future. With miniaturization of devices, it should be easy to replace the phone with an NFC-enabled smartwatch: one watch with NFC has already appeared on the market.

Unfortunately, there is no solution for iOS so far — Apple’s iPhone 6 NFC chip is restricted to Apple Pay and cannot be used in other apps.

Work and photos by DeeBee.it.
Published with permission.

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