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What is a Continuous Glucose Monitor?

What is a Continuous Glucose Monitor?

Testing & Tracking Weight & Metabolism
Written by AgelessRx Last Updated: August 14, 2026

Quick overview of what you’ll learn from this blog post:

  • What is a Continuous Glucose Monitoring system (CGM)?
  • What are the longevity benefits of using a CGM Sensor?
  • How does it work?

What is a Continuous Glucose Monitoring system (CGM)?

A Continuous Glucose Monitoring system, also known as CGM sensor, has become a popular device for health and longevity conscious individuals. The CGM sensor uses a thin, flexible filament inserted just under the skin to measure glucose levels every minute.

Using a smartphone or a standalone reader, you simply scan the CGM sensor at any time to get real-time readings on your glucose levels. The device was initially created for diabetics (replacing fingersticks) but is being used by many who are seeking actionable insight as to how lifestyle choices affect their blood glucose levels.

What are the longevity benefits of using a CGM Sensor?

CGM sensors provide real time results, along with a complete overview of your glucose levels, without ever needing to use a fingerstick. Not only does it show where your glucose is, it keeps record of your glucose history, and can indicate how it’s changing.

The easy and pain free monitoring allows you to determine how your diet, fasting, exercise, and stress influence your blood glucose levels. Furthermore, the comprehensive readings enable you to make better educated and informed changes to your lifestyle. Additionally, healthy blood sugar levels prevent weight gain and reduce the risk of type 2 diabetes.

Currently prescribed Metformin? If so, CGM sensors can be helpful to dial in the proper dosage (e.g. you may find that 1,500mg/day gives you optimal results over 1,000mg/day, for example). Be sure to consult with your doctor or healthcare professional prior to making any adjustments to your dose.

How does it work?

To use a CGM sensor, such as the 14-day FreeStyle Libre from Abbott, you use an NFC Enabled Smartphone (or other device), and the LibreLink app to effortlessly view your readings from the sensor. The CGM sensor can be worn for up to 14 days on the back of your arm. It measures interstitial fluids under the skin to provide readings, while exercising, showering, and even swimming.

What type of CGM does AgelessRx carry?

CGMs are considered a medical device and, as such, a prescription is required. With AgelessRx, you can request a CGM prescription and, if approved, have the order fulfilled at one of our partnering pharmacies and shipped directly to you at home.

Setting Up and Sharing Data With Your CGM App

Once your CGM sensor is applied, you’ll pair it with your NFC-enabled smartphone using the FreeStyle LibreLink app. After inserting the sensor, simply open the app and follow the on-screen prompts to activate it. From there, scanning the sensor with your phone brings up your current glucose reading along with a trend arrow showing whether your levels are rising, falling, or holding steady, plus color-coded ranges so you can see at a glance where you stand.

The app also makes it easy to keep your care team in the loop. Through the free LibreLinkUp app, you can share your glucose data directly with your doctor or a loved one, and detailed reports with charts and averages may help give a provider more context on your readings. This can support tracking how diet, exercise, or a new medication regimen is affecting your levels between checkups.

FreeStyle Libre 2 vs. FreeStyle Libre 3: What’s the Difference?

If you’re deciding between the FreeStyle Libre 2 and the newer FreeStyle Libre 3, the biggest differences come down to size, connectivity, and reported accuracy. The Libre 3 sensor is significantly smaller, about the size of two stacked pennies compared to the Libre 2’s larger profile, and it no longer requires a separate reader. Instead, it sends readings straight to a companion app on your smartphone.

The Libre 3 also has a longer Bluetooth range, staying connected up to about 33 feet from your phone versus roughly 20 feet for the Libre 2, giving you a bit more freedom to move around your home without losing your connection. Abbott reports the Libre 3 has a lower mean absolute relative difference (MARD), a common industry measure of CGM accuracy, than earlier FreeStyle models, though individual results can vary. If you’re an existing AgelessRx subscriber, upgrading to the Libre 3 doesn’t change your subscription price.

To learn more, or to request a CGM prescription, click here.