Dexcom vs. FreeStyle Libre: What to Know About These CGMs

Continuous glucose monitors (CGMs) are monitoring devices people with diabetes use. They apply them directly to the skin and monitor their blood glucose (blood sugar) readings in real time.

Dexcom's CGM and Abbott's FreeStyle Libre are widely used brands of CGM systems. These two systems have many similarities. They are both used as a replacement for blood glucose testing to provide real-time data for people with diabetes.

The key differences between Dexcom and FreeStyle Libre include sensor characteristics, frequency of readings, and types of alerts and alarms.

This article explains what CGMs are, highlights the similarities and differences between Dexcom and FreeStyle Libre (including their accuracy), and provides an overview of CGM insurance coverage.

What Are Continuous Glucose Monitors?

CGMs are wearable devices that are applied to the skin and provide continuous real-time access to blood sugar readings.

These devices provide full access to blood sugar data that can't be captured by only using a traditional glucose meter. CGM data has proved more effective at assessing diabetes treatment success than the hemoglobin A1C test.

CGM data can also help providers personalize treatment plans for their patients. They are typically recommended for use in those who require insulin to manage their diabetes.

Because CGMs do not require multiple finger sticks, they are an attractive option for those requiring frequent blood sugar monitoring.

Other benefits of CGM use include:

• Ease of use
• Ability to simply track blood sugar trends
• Ability to detect readings that are too high or low
• Ability to reduce the impact of long-term complications associated with fluctuating readings

Still, you should have access to blood glucose monitoring in instances in which a CGM reading may be inaccurate, like if the device gives you a warning alert or you're switching insulin doses. You may need to compare CGM results with finger-stick testing and a blood glucose meter.

Types of CGM

CGM types are classified based on how they store and display blood sugar information.

There are three types of CGMs:

• Real-time CGMs that display data automatically
• Intermittent scan CGMs that require the CGM to be scanned often to view and store data
• Professional or provider-driven CGMs that are used for short periods, and providers must download data to review it
  

Provider and individual preferences, lifestyle factors, and insurance coverage may influence the choice between these CGM systems for effective diabetes management.

CGM Components

CGMs consist of a sensor, a transmitter, and a receiver.

The sensor is inserted underneath the skin, typically on the abdomen or arm, with an adhesive that secures it. Sensors measure the glucose levels of fluid surrounding your body’s cells.

The glucose levels of this fluid closely mimic glucose levels in the blood. Sensors are for temporary use and must be replaced as directed.

The sensor connects with the transmitter, which wirelessly transmits the data to a receiver or compatible smart device.

This means that, for the most part, there's no need for frequent finger sticking. However, some CGM models require a finger stick with a glucose meter to help ensure data accuracy.

The receiver then collects the data from the sensor and displays it in real time, allowing continuous glucose monitoring.

CGMs are durable and can be worn throughout the day. They do not need to be removed while exercising, showering, or sleeping.

Examples of available CGMs include Dexcom and FreeStyle Libre, two commonly used CGM systems.

What Is Dexcom?

Dexcom's CGM systems include sensors for placement on the back of the arm or lower abdomen. They also include the option of placing sensors on the upper buttocks when used in children.

The sensors may be used for up to 10 days and do not require calibration. Both systems have smartphone capabilities and applications for data monitoring and sharing.

Available Dexcom CGM products include:

• Dexcom G6 (adults and children 2 years and older)
• Dexcom G7 (adults and children 2 years and older)

Dexcom CGM products require a prescription.

What Is FreeStyle Libre?

Abbott's FreeStyle Libre CGM systems include sensors intended for placement on the back of the upper arm.

Most of the sensors may be used for up to 14 days and do not require calibration, with the exception of the newest Libre sensor (Libre 2 Plus) that became available earlier this year. It can be used for up to 15 days, setting it apart from the other Libre sensors.

Like Dexcom's, each system has smartphone capabilities and data monitoring and sharing applications.

Available FreeStyle Libre CGM products include:

• FreeStyle Libre 14 Day (adults 18 years and older)
• FreeStyle Libre 2 (adults and children 4 years and older)
• FreeStyle Libre 3 (adults and children 4 years and older)
• FreeStyle Libre 2 Plus (adults and children 2 years and older)

Similar to Dexcom's CGMs, these require a prescription from your healthcare provider.

A Word From Verywell

People who would benefit the most from CGMs include those with difficulty managing their blood sugar, people on intensive insulin therapy, or those with hypoglycemia unawareness.

— FEMI AREMU, PHARMD, MEDICAL EXPERT BOARD

Dexcom vs. FreeStyle Libre: Key Differences

In general, GCM systems work similarly, and both systems provide valuable data. However, there are some key differences between Dexcom and FreeStyle Libre.

Frequency of Glucose Readings

Dexcom systems are real-time CGMs and track blood glucose continuously throughout the day, obtaining data as often as every five minutes. Glucose readings update automatically.

The Libre systems automatically report readings up to every minute, except for the FreeStyle Libre 14 Day. The FreeStyle Libre 2 requires the sensor to be scanned for readings to update.

Sensor and Transmitter Characteristics

Dexcom sensors last up to 10 days, while FreeStyle Libre sensors last up to 15 days.

The Libre 2 Plus connects to the Tandem t:slim X2 insulin pump and corresponding mobile app.

Appropriate Use

Both Dexcom systems can be programmed to work with insulin pumps, whereas only the FreeStyle Libre 2 Plus system is compatible with an insulin pump.

Both Dexcom and FreeStyle Libre can be safely used in children as young as 2 years.

The U.S. Food and Drug Administration (FDA) has approved Dexcom G7 and FreeStyle Libres 2 and 3 for use during pregnancy.

Which Is More Accurate?

Both Dexcom and Libre can provide reliable and precise continuous glucose monitoring. Factors such as proper sensor use and calibration, proper insertion technique, and sensor location can influence accuracy.

A recent clinical trial evaluated the accuracy of one of each of the Dexcom and FreeStyle Libre CGM systems. The study investigators compared their CGM readings with blood sugar readings.

Though both devices were highly accurate, study results revealed that the FreeStyle Libre 3 was more precise than the Dexcom G7.

When determining which CGM is right for you, you and your provider might consider factors such as personal preference, specific health needs, and cost. Research your options and discuss them with your diabetes care provider.

CGM data should be monitored under the supervision of a healthcare provider.

Does Insurance Cover CGMs?

Coverage for CGM systems by insurance varies depending on factors such as:

• Type of insurance (such as private or government funded)
• Insurance provider
• Coverage terms and details
• Individual medical necessity

Many insurance plans offer coverage for CGM devices for people requiring intensive insulin therapy that usually includes multiple daily insulin doses.

Coverage may depend on specific criteria, such as documented uncontrolled diabetes, an unawareness of hypoglycemia, or frequent blood sugar fluctuations. Some plans may cover certain CGM brands or models, while others may not.

Some insurance plans may require you to fill your CGM prescription through a durable medical equipment (DME) distributor rather than a traditional pharmacy.

Review your insurance policy and familiarize yourself with what your insurance covers. Consult with your diabetes care provider and work with insurance representatives to determine coverage options and the most up-to-date requirements for CGM devices.

Summary

The number of people living with diabetes who use CGMs continues to increase. CGMs have evolved as a less invasive way to optimize blood sugar control and provide real-time data while minimizing the need for traditional blood glucose monitors.

Dexcom and FreeStyle Libre CGMs are widely used and have gained popularity because of their convenience, simplicity, and ease of use. Obtaining CGM readings can also be less painful than using a traditional blood glucose monitor.

Both adults and children can use Dexcom and Freestyle Libre with a valid prescription. Key differences between Dexcom and FreeStyle Libre include how often they upload data, how long the sensors last, and who can use them safely.