February 27, 2024

Different Types of CGM: A Complete Guide

What is the Best Continuous Glucose Monitor (CGM) for Your Diabetic Needs? It’s a fact of life – people with diabetes need to check their glucose levels every so often. In the past, that meant doing multiple finger-prick tests per…

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Home / Living with Diabetes / Different Types of CGM: A Complete Guide

What is the Best Continuous Glucose Monitor (CGM) for Your Diabetic Needs?

It’s a fact of life – people with diabetes need to check their glucose levels every so often. In the past, that meant doing multiple finger-prick tests per day. But these tests are inconvenient and painful, so it’s not hard to see why you’d want to reduce your reliance on them.

With that in mind, more and more people with diabetes have started using continuous glucose monitor (CGM) systems in recent years. These systems offer similar functionality to standard glucose meters while nearly eliminating the finicky testing process the older devices are known for. Are you interested in buying a CGM but want to ensure you’re getting the best continuous glucose monitor for your needs? If so, check out this complete guide to the different types of CGM curated by the pros at US MED.

What is a CGM?

At the most basic level, a CGM is a device that helps you watch your glucose levels throughout the day. For the most part, wearing a CGM will allow you to check how high or low your blood sugar is without completing a finger prick test. With various types of CGM to choose from, it can get confusing, so read on to learn more and discover the right CGM for you.

How much does a CGM cost?

It’s hard to say quite how much a CGM will run you. These products – and the supplies you’ll need to keep using them – can vary significantly from one brand to the next. Still, you can safely assume a CGM will cost more than a traditional glucose meter.

That said, you might not have to pay for a new CGM at all! These days, quite a few insurance plans cover CGMs for eligible patients. If that’s the case for you, US MED services Medicare and countless other insurance plans.

How to choose the best continuous glucose monitor and meter for you

The process of buying a CGM might feel overwhelming, but it’s not that different from shopping for any other big-ticket item. Just look at the options on the market, consider their pros and cons, and determine which product best fits your needs.

Of course, CGMs are medical devices, meaning it can be easy to get bogged down in jargon. To avoid confusion, read on for our straightforward overview of three leading CGMs available today.

CGM brands

FreeStyle Libre 2 system

The FreeStyle Libre 2 system takes everything you know and love about the FreeStyle Libre 14 day system and brings it to the next level. This system introduces features like optional alarms, iCGM capabilities, and more while continuing to offer trustworthy glucose readings.§

However, there’s one catch: the FreeStyle Libre 2 system won’t be Abbott’s most advanced CGM system for much longer. The FreeStyle Libre 3 system, which will introduce features like thinner sensors and real-time smartphone readings, recently received FDA clearance. Still, if you want to start using a CGM as soon as possible and don’t care about keeping up with the hottest diabetes treatment technology, this system should serve you well for years to come.


Like the FreeStyle Libre 14 day system, Abbott strives to keep the FreeStyle Libre 2 system affordable – even without insurance. The cost of this CGM is 70 percent lower than the list price of other CGM systems.¶,‡




  • Includes: FreeStyle Libre 2 reader, USB cable, power adapter, user’s manual, additional usage guides
  • Reader Operating Temperature: 50°F-113°F
  • Reader Power Source: Lithium-ion battery (rechargeable)
  • Reader Size: 95 mm x 60 mm x 16 mm
  • Reader Weight: 65 g
  • Sensor Operating Temperature: 50°F-113°F
  • Sensor Power Source: Silver oxide battery
  • Sensor Reading Range: 40-400 mg/dL
  • Sensor Size: 5 mm height, 35 mm diameter
  • Sensor Weight: 5 g



FreeStyle Libre 2 Plus sensor

Pros & cons

Technically, the FreeStyle Libre 2 Plus sensor isn’t a CGM in its own right—instead, this product is a revised version of the original FreeStyle Libre 2 sensor. These updated sensors come with some exciting improvements, such as compatibility with the Tandem® t:slim X2® insulin pump and an overall mean absolute relative difference (MARD) of 8.2 percent compared to their predecessor’s combined MARD of 9.3 percent||. And with a 15-day lifespan, the FreeStyle Libre 2 Plus sensor lasts longer than any other sensor in Abbott’s history.


Despite these improvements, the FreeStyle Libre 2 Plus sensor still falls behind the FreeStyle Libre 3 system in a few key areas. Take its MARD, for example—the FreeStyle Libre 3 boasts an even lower overall MARD of 7.9 percent#. But if you want to get the most out of your FreeStyle Libre 2 system, switching to FreeStyle Libre 2 Plus sensors is an easy way to keep using this system while unlocking some new capabilities.


As is the case for other Abbott sensors, the FreeStyle Libre 2 Plus sensor is covered by insurance and Medicare for eligible patients**,†† with a prescription. Your out-of-pocket expenses will vary based on your insurance coverage.

Freestyle Libre 2 Plus



  • Sensor Wear: Up to 15 days
  • Bluetooth Range: 20 ft
  • Data Storage: Eight hours
  • Sensor Size: 35 x 5 mm
  • Reader/Receiver: Libre 2 App, Libre 2 reader, or Tandem t:slim X2 insulin pump
  • Age of Patient: Two years and up
  • Vitamin C Warning (US Only): >1000 mg



FreeStyle Libre 3 system

Pros & cons

When you use the FreeStyle Libre 3 system, you’ll get an updated glucose reading every minute—no scan required. Unlike previous FreeStyle Libre systems, the sensors used in this system can automatically transmit glucose updates to your reader or smartphone. These sensors are also about as big as two stacked pennies, which makes them the thinnest, smallest CGM sensors ever made‡‡.


Since the FreeStyle Libre 3 system is Abbott’s most advanced CGM system yet, it doesn’t suffer from many notable disadvantages. However, its sensor lifespan is slightly shorter than the service life of FreeStyle Libre 2 Plus sensors.


Most commercially-insured patients will pay anywhere between $0 and $75 per month for FreeStyle Libre 3 sensors,¶¶. This system is also eligible for reimbursement for qualifying Medicare beneficiaries**,††.


  • Sensor Size: 2.9 mm height and 21 mm diameter
  • Sensor Weight: One gram
  • Sensor Power Source: One silver oxide battery
  • Sensor Life: Up to 14 days
  • Sensor Memory: Up to 14 days (glucose readings stored every 5 minutes)
  • Operating Temperature: 10°C to 45°C


Dexcom G6

Pros & cons

The Dexcom G6 is another industry leader in the CGM field. Like the FreeStyle Libre 2 system, this device delivers notifications when your glucose level is getting too high or low. You can also send updates on your glucose levels to loved ones with the Dexcom Share feature.#

Before purchasing the Dexcom G6 system, it’s worth keeping in mind that its sensor application process involves more steps than that of the FreeStyle Libre systems.**,††,‡‡If you plan to buy a CGM without insurance, this option may also be more expensive than the FreeStyle Libre 2.¶,‡


If you’re planning to invest in a Dexcom G6, you’ll want to double-check your insurance coverage. Fortunately, Medicare covers this CGM system; the same is true for many private insurers in America.


  • Receiver Dimensions: 10.67 cm (L) x 6.35 cm (W) x 0.15 cm (H)
  • Receiver Memory Storage: 30 days of data
  • Receiver Operating Temperature: 32°F – 113°F
  • Receiver Weight: 113.4 grams
  • Sensor Lifespan: Up to 10 days
  • Transmitter Dimensions: 4.57 cm (L) x 3.05 cm (W) x 1.52 cm (H)
  • Transmitter Operating Temperature: 50°F – 107.6°F
  • Transmitter Weight: 28.35 grams (sensor included)




Dexcom G7

Pros & cons

The Dexcom G7 system is the newest type of CGM on the market. This system builds on its predecessor by offering a higher level of accuracy than any other CGM system in America***, sensors 60 percent smaller than those found in the Dexcom G6 system, and a warm-up time that’s twice as fast as competing systems†††.


If the Dexcom G7 has a weakness to speak of, it’s the fact that its sensors’ adhesive patches are also smaller than those found on the Dexcom G6—making them slightly more likely to fall off as a result. To reduce this risk, diabetes patients should use the “overpatch” that comes with their sensors.


Like any CGM system, your Dexcom G7 pricing will vary based on your commercial health insurance plan. If you have Medicare coverage instead, the Dexcom G7 is covered for eligible patients‡‡‡. And if you have no CGM coverage, Dexcom can help you save more than $200 per month¶¶¶ on this system with its Pharmacy Savings program.


  • Glucose Range: 2.2–22.2 mmol/L
  • Receiver Memory Storage: 180 days of glucose data
  • Receiver Lifespan: Three years (assuming typical use)
  • Sensor/Transmitter Dimensions: 24 × 27.3 × 4.6 mm
  • Sensor/Transmitter Battery Lifespan: 10 days, plus a 12-hour grace period
  • Sensor/Transmitter Operational Temperature: 50-107.6°F


What was types of CGM were left out of this list?

As you might expect, these aren’t the only types of CGM available on the market today. However, we here at US MED believe these are the best products you can find in this category. While it can be a good idea to try to find the biggest bargain when shopping for some items, that’s not the case when your health is on the line. Any one of the CGMs listed above will do an admirable job of measuring your blood sugar – the key is finding the best CGM device for your needs.


This list also omits “traditional” glucose meters. That is due to the list’s focus on more advanced glucose measurement technologies, but there’s no reason why you can’t continue using these devices if you don’t mind doing finger-prick tests. Given these CGMs measure interstitial fluid (ISF) you may need to use a traditional glucose meter to double-check your readings when your symptoms don’t match your numbers.

Where should I place the sensor?

The location of your CGM sensor will depend on the type of system you use. For the FreeStyle Libre systems, Abbott recommends applying sensors to the back of the upper arm. On the other hand, you’ll usually apply Dexcom G6 sensors to the abdomen (or on the upper buttocks, for Dexcom users aged 2-17). Either way, you’ll need to place your sensors in a slightly different position each time you replace them to avoid scarring and irritation.

How to see the glucose reading

Seeing your glucose numbers is easy with any of these types of CGM. With a FreeStyle Libre-brand CGM, you’ll scan your sensor with a smartphone or dedicated device. Meanwhile, Dexcom G6 results will automatically appear on your phone or other monitor.

How often should I change the sensor?

As the FreeStyle Libre 14 day system’s name suggests, sensors for this system will last up to 14 days. That’s also the case for the FreeStyle Libre 2. Dexcom G6 sensors have a slightly shorter lifespan, lasting up to 10 days. The wireless transmitter used with these sensors can last for three months.

Compatibility with phones and devices 

You can find device compatibility information on Abbott and Dexcom’s respective websites.

Why choose US MED for your CGM needs?

No matter what type of CGM you need, there’s no better place to buy it than US MED. Throughout the past 20 years, we’ve gained a reputation for being the most reliable diabetes supply company in America, thanks to our direct billing capabilities and total satisfaction guarantee. More than a million diabetes supply customers can’t be wrong – start shopping for the products you need at US MED today!


*Taking high levels of aspirin may cause false low readings and high levels of Vitamin C may cause false high sensor readings. Refer to the FreeStyle Libre 14 day system user manual for more information.

Based on a comparison of list prices of the FreeStyle Libre 14 day system versus competitors’ CGM systems. The actual cost to patients may or may not be lower than other CGM systems, depending on the amount covered by insurance, if any.

Data on File. Abbott Diabetes Care.

  • High levels of vitamin C may affect the accuracy of sensor readings. Refer to the FreeStyle Libre 2 user manual for more information.

Based on a comparison of list prices of the FreeStyle Libre 2 system versus competitors’ CGM systems, assuming annual use of one receiver (or equivalent hardware) and quantity of transmitters and/or sensors according to use life.

#Dexcom Share is a Dexcom G6 app feature that lets users share their glucose data with up to 10 designated people, or “followers.” When your followers download the Dexcom Follow app to their compatible smart devices, they can remotely monitor your glucose data.

**FreeStyle Libre 2 User’s Manual.

††FreeStyle Libre 14 day User’s Manual.

‡‡Dexcom G6 CGM User Guide.

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