Takeaways

• Continuous glucose monitoring (CGM) has revolutionized diabetes care by providing users with (nearly) real-time information on their blood glucose levels.

• Dexcom G6 and Abbott FreeStyle Libre are two widely used FDA-approved fingerstick-less CGM systems.

• Although comparable, the two systems differ in several key ways, which users must consider when choosing between them.

• The Dexcom G6’s advantages over the FSL include better accuracy, ease of use, more customizable alerts and alarms, real-time data, and compatibility with insulin pumps.

• On the other hand, the FSL triumphs over the Dexcom G6 in terms of sensor lifespan, size, remote sharing of glucose data (i.e., 20 people versus 10 in the Dexcom G6), warm-up time, accessibility, and cost.

The ability of continuous glucose monitoring (CGM) to track users' blood glucose levels in (almost) real-time has revolutionized diabetes care. It allows people with diabetes—i.e., users—and their respective healthcare teams to:

• Identify blood glucose trends (e.g., fluctuations in response to particular foods) and make appropriate lifestyle or medical interventions

• Lower the number of hypoglycemic episodes

• Determine users’ ideal glucose range (note: studies show that “normal” sugar levels may not be optimal for everyone)

If you have diabetes, the benefits mentioned above make a compelling case for the use of a CGM. The only problem? With the sheer number of devices available in the market, picking one that's most suited to your needs can be tricky. 

For instance, chances are you've heard about the massively popular Dexcom G6—but is it any good? Also, how does it compare against the Abbott FreeStyle Libre, another fiercely in-demand glucose monitor? You're in luck. 

In this article, we cover what you can expect from the Dexcom G6, then compare it with the Abbott FreeStyle Libre so that you can select the right system for you. 

Dexcom G6 and Abbott FreeStyle Libre (FSL) overview 

The Dexcom G6 is an FDA-approved CGM system for individuals aged 2 or over. You can wear the sensor either on your upper arm, abdomen or upper buttocks.

The following components make up the G6:

• Sensor and auto-applicator: Each sensor comes with a plastic orange and white auto-inserter. A single-push button inserts the sensor’s tiny cannula into the skin.

• Adhesive: A medical patch holds the Dexcom G6 sensor in place. This allows you to go about your daily routine without worrying about the sensor falling out.

• Transmitter: Every 5 minutes, the sensor sends glucose readings to the mobile app (CLARITY) via Bluetooth through a transmitter. Users should dispose of the transmitter when its battery—which typically lasts 3 months—runs out.

On the other hand, the Abbott FreeStyle Libre is FDA-approved for personal use on the back of the upper arm. The system uses wired sensing technology to measure glucose levels. Its main components include:

• A small and discreet disposable sensor: Users scan this with the NFC sensors of their phones with the FreeStyle Libre app open—refer to this article for more information.

• Easy-to-use applicator

Dexcom G6 vs Abbott FreeStyle Libre (FSL) Review

Shared features

1. No fingerstick calibrations: Studies show fingersticks are a major point of inconvenience among users seeking to track their glucose levels. Luckily, both Dexcom G6 and FSL are factory-calibrated, negating the need for any fingersticks.

2. Improvements in glycemic control: The G6 system users report improvements in all measurable glycemic indexes. Similarly, studies show improved treatment satisfaction and lower episodes of hypo- and hyperglycemia among FSL users.

3. Water-resistant: Two major components of these CGM systems are water-resistant: the sensor pod and transmitter. This means they can withstand water up to a depth of 1 meter for 30 minutes or less. In other words, users can shower and swim with the device attached. 

4. Pregnancy-safe: Both Dexcom G6 and the FSL are safe to use in pregnancy in the US and many other countries. In Singapore, use of CGM in pregnancy is currently off label.

5. Resistant to interference from acetaminophen: Acetaminophen is a routinely used pain-killer that can falsely elevate CGM readings. Luckily, both the Dexcom G6 system and FSL are resistant to interference from acetaminophen.

6. Past glucose level information: CLARITY is Dexcom’s exclusive app that syncs with the G6 sensor, while the LibreLink app syncs with the FSL sensor. Both apps can help users easily track and understand their glucose levels over several months with interactive charts and tables. Users can also share their data with their family or healthcare providers, and set alarms when their blood sugar exceeds a certain range.

Pros of the Dexcom G6

1. Accuracy: Mean absolute relative difference (MARD) is a universal performance standard for CGM systems. A lower number indicates higher accuracy. Dexcom G6 has a MARD rating of 9%, while FSL has a MARD rating of 9.2%—meaning the former is more accurate. Better yet, a 2021 study of 218 individuals with diabetes showed that the G6 readings were comparable to direct blood testing 98% of the time.

2. Real-time tracking: The FreeStyle Libre is not a CGM system in the strictest sense; instead, it’s a flash glucose monitor. While it takes glucose readings every minute, it only transmits data when users scan the sensors. That translates to the risk of losing readings over time if you forget to scan the sensor regularly. Compare that to the Dexcom G6, which provides actual, real-time tracking; it automatically sends glucose level readings every 5 minutes—no sensor-scanning necessary. 

3. Suitable for everyone aged 2 and above: The Dexcom G6 is FDA-approved for all adults and children aged 2 or over. On the other hand, the FSL is only approved for use in children and adults aged 4 or over.

4. Resistant to interference from X-rays: The G6 CGM components retain functionality and data integrity even after exposure to X-rays. This means routine diagnostic imaging and airport security checks won't interfere with the results. However, with the FSL, you’re advised to remove its sensors before exposure to X-rays as they may damage the sensor—and adversely impact its ability to detect trends and track patterns in glucose values during the wear period.

5. More customizable alert settings: The Dexcom G6 comes with 4 types of alerts. The 2 factory-set alerts are the “urgent low” alarm, which sounds when the CGM reading is at or below 3.1 mmol/L (55 mg/dL), and the “urgent low soon” alarm, which sounds when the system predicts readings to fall below 3.1 mmol/L (55 mg/dL) within 20 minutes. The “low” alarm and the “high” alarm are where users define what low and high blood glucose levels look like for them, respectively. On the contrary, the FSL does not come with automatic (or customizable) alerts and alarms to indicate when glucose levels are too low or high. This can be dangerous to individuals prone to hypoglycemia, like those with type 1 diabetes or children.

6. Interoperability with insulin pumps: Dexcom G6 can work with insulin pumps that automatically administer insulin when glucose readings become too high (enabling fuss-free insulin management). This contrasts with the FreeStyle Libre, which is incompatible with any other device.

Cons of the Dexcom G6

1. More frequent changing of sensors: The Dexcom G6 sensor lasts 10 days, while the FSL sensor lasts 14 days. That means G6 users will have to change their sensors more frequently. 

2. Larger size: The Dexcom G6 measures 70 mm x 40 mm x 10 mm, and weighs 11.9 grams. On the other hand, the FSL comes in at a much more manageable weight of 5 grams, with a diameter of 35 mm and a height of 5 mm.

3. Limited remote sharing: With the LibreLink app, users can share data with up to 20 people (twice as many as Dexcom G6).

4. Longer warm-up time: FreeStyle Libre 2 has a 1-hour warm-up period before it starts generating data. This time is 2 hours for the Dexcom G6. 

5. Accessibility: FSL is available over the counter. On the other hand, users can only purchase the G6 from healthcare providers in Singapore.

6. Cost: The G6 costs US$299/month. On the other hand, FSL costs roughly US$130/month.

Is the FSL right for you?

A significant advantage of the FSL over the Dexcom G6 is its 14-day sensor life. Thus, it is the preferred option for you if you want to avoid having to replace your sensors more frequently. Additionally, the lower monthly cost means it may be better for some people without insurance. The FSL also has a slimmer profile and may be the preferred option for individuals concerned about the size of the wearable.

Is the Dexcom G6 right for you?

The Dexcom G6 is a comprehensive CGM system that’s arguably easier-to-use than the FSL, requiring little user input to record and track readings. Its automatic alert and alarm features provide a valuable safety net against hypoglycemia, thus, making it the obvious choice for children and those with type 1 diabetes or who are on insulin.