What is a CGM?

It stands for Continuous Glucose Monitor

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This post was reviewed by our Director of Clinical Excellence and Oversight.

CGM is the acronym that’s been gaining attention among people with diabetes. It stands for continuous glucose monitor, and many healthcare plans cover them. They are great for people who need to check their glucose levels frequently, but what are they exactly?

Maybe you tried a CGM a while ago and found it wasn’t for you. But improvements have you curious. Or maybe you’ve heard of a CGM already, but are a little fuzzy on how it works. Either way, we’ve got you covered in this post.

CGM - Continuous Glucose Monitors

CGM Basics

No matter the brand that you choose, real-time CGMs work in basically the same way. There are three main parts of your CGM:

  • The monitor or an app on your smart device. This is where you read your current blood sugar level, historical readings, and check out trends that can predict when your blood sugar will rise and fall.
Dexcom glucose monitor
  • The sensor is a small cannula wire that lives under the skin and detects your blood sugar level.
Dexcom G6 CGM sensor
  • The transmitter is connected to the sensor and sends the information to the device you are using, either a monitor or your phone. (This is not a part of intermittent monitors, those differences will be explained in the next section.)
Dexcom G6 CGM transmitter

CGMs could replace or reduce your fingerstick monitoring with automatic frequent readings. The constant monitoring makes it possible to track trends in blood sugar highs and lows. Some CGMs have alarms that can be programmed to alert the patient or their caregiver if blood sugar levels change dramatically, and as of 2016, patients can manually inject their insulin based on readings from a CGM. 

Intermittent vs. Real-Time

There is one main way that CGM devices are different. Some are intermittent monitors, while others are real-time monitors. Here’s what that means:

  • Intermittent: With an intermittent monitor, you scan the sensor with a reader or smartphone to see your glucose level. This means there are no alarms with this type of CGM; you check your levels manually.
  • Real-time: A real-time monitor is consistently tracking your levels and alerting you about any significant changes. Alarms go off to let you know if there is an issue with your glucose level.

There are pros and cons to both types of CGMs. If you are considering using a CGM, it is best to talk with your doctor about the kind that is right for you.

Knowledge is Power

The benefits of using a CGM are numerous: The freedom of potentially reducing or eliminating the need for fingersticks can save time and money. The continuous monitoring shows the patient or the caregiver exactly how meals, physical activity, medication, and time of day affect your blood sugar level. With this information, you and your doctor can work on a treatment plan that is customized to you.

A CGM can also help you be more active because of its ability to predict how quickly blood sugar is rising or falling. Imagine knowing where your blood sugar will be an hour from now before going on a hike or hitting the gym. This feature can help you or your loved one avoid potentially life-threatening situations.

For the parents of children living with Type 1 Diabetes, a real-time CGM could deliver peace of mind. When children are in school or at a friend’s house, it’s easy to imagine the worst, especially when your child needs to keep track of their blood sugar levels on their own. Using a real-time CGM, a parent can pick up their phone and check on their child’s blood sugar levels even when they are miles away.

A Long-Time Coming

It might feel like CGMs hit the scene in a hurry, but in reality, these innovative devices have been on the market since 1999. But, it’s only since 2018 that the FDA approved CGMs that could be worn for up to 90 days. In other words, if you have tried a CGM in the past and didn’t feel like it was right for you, it might be time to give one of the upgraded models a try. And if you’ve never used a CGM but are ready to give up using lancets and fingersticking, talk to your doctor today. You can learn even more about these innovative devices by reading our CGM guide.

For more information on diabetes management, check out our diabetes fact sheet.

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