The “what, why and which one” on Continuous Glucose Monitors (CGM’s)

Continuous Glucose Monitors

It’s Diabetes Month, which feels like a good time to revisit the deets on continuous glucose monitors – what are they, are they helpful for those without diabetes, and which one do we recommend?

The What: A CGM, or continuous glucose monitor, is a glucose sensor applied to the belly or arm, with a very small needle (described by Dexcom, one of the companies that makes them, as “soft and flexible like a kitten’s whisker”) to continuously measure glucose levels in the interstitial fluid of the tissue just below the skin.  Newer monitors are worn 10-14 days and can now send data wirelessly to an app on your phone. 

The Why: The ability to see changes in blood glucose on a real-time basis has the potential to provide immediate feedback to users on food choices and physical activity.  For patients with prediabetes, or those who simply wish to better understand how best to achieve steady, healthy range blood glucose throughout the course of the day and avoid large glucose fluctuations, CGMs can provide valuable data that can help you make good diet and exercise choices and can help you feel your best (e.g. timing the right amount of energy snack at the right time).  UCSF’s Vice President of Digital Health and Associate Professor of Endocrinology, Aaron Neinsten, wrote, “With rapidly improving CGM technology, wireless data upload, lower-cost CGM devices, and the availability of digital coaching tools, we believe the time is ripe for CGM use in a much broader population, including those with T2D who are on oral medications and those with prediabetes. Although additional studies will need to be done to demonstrate benefit in these populations, costs will likely continue to fall and technology will continue to improve, only further strengthening the value proposition for wider CGM use.”

Which one: Dexcom (G6 or G7) and Freestyle (Libre 2 or 3) are the most common Continuous Glucose Monitors (CGMs) used.  One of the main differentiators used to be that the Libre system required holding your phone over the device to scan your blood glucose reading in order to see it, whereas the Dexcom system provided real-time data uploaded to your phone automatically every 5 minutes. The Libre system has now been updated to automatically upload your blood glucose reading to your phone’s app every minute.  Dexcom’s iPhone app, Clarity, syncs with the G6/G7 sensor, while the LibreLink app syncs with the Freestyle sensor. Both apps can help users track and understand their glucose levels over time with interactive charts and tables, share their data with their healthcare provider, and set alarms when their blood sugar exceeds a certain range.  Dexcom’s iPhone app receives higher user ratings.  Both are covered by insurance for eligible patients (typically those with diabetes), there are savings programs for each that can be taken advantage of when insurance does not cover them, and Freestyle currently has a Free Trial Program for the first sensor for most patients.

If interested, ask your friendly Village Doctor MDs for more information on whether trying a continuous glucose monitor (CGM) might be right for you!

Read Also: Nutrition On-the-Go

Jennifer Abrams, MD, November, 2023

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