What is CGM? How is it different from BGM?

Continuous glucose monitoring (CGM) automatically tracks blood sugar levels throughout the day and night. A small sensor is placed under the skin which tests the sugar levels in the interstitial fluid. Through CGM, you can see changes and trends in your blood sugar over time which can help get a better handle on your diabetes.

On the other hand, blood glucose monitoring (BGM) tests sugar levels in the blood through fingersticks and measures your glucose levels at a single moment in time.

FreeStyle Libre System Overview

The FreeStyle Libre System is a continuous blood glucose monitoring device for people with Type I and Type II diabetes. A small sensor is placed on the back of the arm and can be scanned with a reader or app on your phone to see real time glucose levels and trends in your glucose levels.

FreeStyle Libre Sensor 

The FreeStyle Libre Sensor is a small device about the size of two stacked quarters. The filament on the sensor is less than 0.4 mm thick and goes into the interstitial fluid, a thin layer of fluid below the skin.

How do I put the sensor on?

1. Choose an area on the back of the upper arm that is free of any moles, scars, or recent insulin injections.
2. Peel the lid off completely from the sensor pack. Unscrew the cap of the sensor applicator and set aside.
3. Line up the dark mark on the sensor applicator with the dark mark on the sensor pack. On a hard surface, press down firmly on the sensor applicator until it comes to a stop.
4. Place the sensor applicator over the chosen site on the arm and press down firmly until the sensor is securely in place.
5. Recap the sensor applicator and discard sensor pack and applicator as appropriate.

Here is a quick link to a video by FreeStyle US: How to Apply the Sensor

Once the sensor is in place, it has a one hour warm up time before any glucose readings can be obtained and the sensor is worn for 14 days then replaced with a new sensor.

The sensor is water resistant up to one meter of water for 30 minutes and can be worn while showering and exercising.

The sensor should be removed prior to MRI, CT scans, X-rays, and diathermy treatments. Additionally, it should be removed for airport security if you are going through the full body scanner. To remove the sensor, gently pull up the edge of the adhesive of the sensor and peel off in one swift motion. It is important to note that the same sensor should not be replaced on skin if it falls off or has to be removed before the 14 days are up. If the sensor falls off early, patients may call the Abbott Diabetes Care line at 1-855-632-8658 for further assistance.

FreeStyle Libre Reader and LibreLink App

The FreeStyle Libre Reader is a small, chargeable device that is used to scan the FreeStyle Libre Sensor to retrieve glucose levels and trends over time. The reader is held close to the sensor and a small sound or vibration will alert you that data has been collected. One sensor at a time can be paired to a reader and the reader will tell you how many days are remaining on the sensor. It will display an alert when three days are remaining, and when eight hours are remaining. The Reader also contains a port for test strips to check blood sugar levels when a check blood sugar symbol is displayed. The port on the Reader is compatible with the FreeStyle Precision Neo test strips.

What does the reader tell me?

• Visual alerts and trend arrows → alerts when glucose levels are getting high, and shows current glucose reading
• Daily patterns graph
• Time in target chart
• Average glucose graph
• Low glucose events graph

Data is stored on the reader for up to 90 days and reports are available to 7, 14, 30 and 90 days.

FreeStyle LibreLink App

The FreeStyle LibreLink App is an app that allows you to use your smartphone to scan your FreeStyle Libre Sensor similar to the Reader. When you open the app, you hold your phone close to your sensor to get a reading. A small tone or vibration will alert you that the data has been transmitted which you can then view in the app. In the app, you can view your current glucose reading, see how your levels are changing, see glucose history from the last eight hours, and add notes to track food, insulin doses and exercise. The FreeStyle LibreLink App is available to download on the Apple App Store and on Google Play.

References:

https://www.freestylelibre.us/system-overview/freestyle-14-day.html

https://www.freestylelibre.us/support/faq.html

https://www.freestylelibre.us/system-overview/continous-glucose-monitor-app.html