Continuous Glucose Monitors (CGM): All Your Questions Answered

Learn why you might want to try a CGM, whether or not you’re on the diabetes spectrum.
What is a CGM | Continuous Glucose Monitor

What you really need to know about continuous glucose monitors (CGM)

In the not-so-distant past, the only way to monitor your blood sugar, aka glucose, level was with constant finger pricks. Eat a meal, wait, use a lancet device to get a drop of blood, place it on a test strip, read the meter. Well, that’s no fun for anyone. Now, it’s easy and painless to get quick readings all day long, thanks to continuous glucose monitors (CGMs). CGMs have been accepted as a way to manage type 1 diabetes for many years now, and research has recently shown that it can be just as effective at helping people regulate type 2 diabetes, too. But what is a CGM, exactly? 

CGMs can provide powerful health information even if you don’t have diabetes or prediabetes. The blood glucose data these devices serve up can unlock learnings for anyone—about which foods allow you to feel your best now, and will help protect you against a host of chronic diseases in the future. If you’ve ever felt frustrated switching from one diet to the next in search of an eating style or plan that keeps your body energized and your weight healthy, a CGM might be the missing link. Its ability to offer a personalized look at how your body responds to different foods has made CGMs increasingly popular beyond just the diabetes community. And for good reason: No two bodies are exactly alike. Your unique biology means you’ll respond differently to the same food than someone else will, thanks in part to genetics, your lifestyle, age, activity level, and the state of your microbiome. So the diet your friend—or an influencer you follow on Instagram—swears by might be all wrong for you. 

You need to discover what’s optimal for your body, and that’s where a CGM comes in. Here, we’ll take a look at the basics of CGMs so you can decide what this breakthrough device can offer you. 

What is a CGM (continuous glucose monitor)?

A continuous glucose monitor is a wearable device that, as the name implies, continuously tracks your glucose levels throughout the day and night. It attaches to your skin through a painless insertion process that takes less than a minute. At most, you’ll feel a little pinch. (January AI uses the Abbott FreeStyle Libre). Once the CGM is on, its sensor wirelessly connects to an app or monitor and transmits up-to-the-minute glucose levels so you have a consistent stream of readouts. Most CGMs have to be replaced every 14 days.  

Using a CGM with Type 2 Diabetes

If you are living with type 2 diabetes, a CGM can be a critical component to your ongoing management of the condition. It makes managing diabetes simpler, with much less guesswork (and no finger sticks!) involved. You’ll be able to see in almost real time how your body responds to what you eat. Did that bowl of oatmeal this morning cause your numbers to go way up? Did a tuna salad at lunch keep things relatively stable? If your levels get too low at night, does apple with peanut butter before bed do the trick? Your CGM can answer all these questions for you. It’s all in the data: You’ll be able to watch your glucose levels and make adjustments to your diet over time. The end result could be a meal plan that’s truly customized to your biology and helps you achieve control over your diabetes. 

Plus, anyone managing type 2 knows that extreme swings in glucose—going too high or too low—can be dangerous. With a CGM, the accompanying app or monitor can alert you if you’re entering into a danger zone, so you’re able to react immediately. 

Using a CGM with Prediabetes

If you’re diagnosed with prediabetes, your doctor will likely advise you to eat better and exercise more to bring your numbers down into the healthy range. But it can be hard to know where to start. Exactly what should you eat? What type of activity is best, how much, and when? You may have counted calories before, but glucose control is about much more than the typical calories in/calories out equation. For all these reasons, a CGM may be your fastest route to understanding how your everyday choices—meals and snacks you grab without thinking—affect your levels. Seeing those dips and spikes in real time will make it crystal clear which foods are going to help you reach your goals and which might be getting in the way of your progress. In fact a 2020 study in the journal JMIR Diabetes found that CGMs helped adults with prediabetes to visualize the effect carbs had on their blood sugar, spurring dietary changes.

The same goes for exercise. You’ll be able to see how your blood glucose levels respond after a short walk, a longer one, a heart-pounding run, or a calming yoga class. “Much like the foods we eat, the response to different kinds of activity is unique to the individual,” says Mazi Saberi, PhD, systems physiologist and Chief Scientific Officer of January AI. “CGM data allows you to see your personal response and use exercise as a powerful tool to manage blood glucose levels.”

At first, you should use your CGM to establish your baseline and get a better understanding of where things stand so you feel empowered to make changes that actually deliver results. The good thing about a CGM is that it shows you the immediate glucose impact of everything you try, so you can experiment and adapt your routine quickly, in ways you know will work for you.

Using a CGM for Overall Better Health

Maybe you’ve never had your blood glucose levels tested by your doctor (usually with an A1C test), or you have and the results fell within a normal range. That’s great. But perhaps diabetes and/or heart disease run in your family and you’re concerned you’re on the path to developing one or both. Perhaps you had gestational diabetes during pregnancy, which raises your risk of developing the disease later in life. You might be living with Polycystic Ovary Syndrome (PCOS) or another condition linked to impaired glucose control, which means managing your blood sugar can help. Or maybe you’re bugged by energy and mood swings, and want to figure out how to eat better to feel better.

These are all valid reasons for trying a CGM to gain more control over your long-term health. It may not make sense for long-term use, but it can provide an eye-opening window into your metabolism and nutritional health—one you’d never be able to access otherwise.  

One thing to remember: A CGM is a medical device, so you’ll need a prescription to purchase it. (And you’ll most likely need to get specific authorization for your insurance to cover it.) That said, it can be prescribed for reasons beyond just diabetes management, and it may be just the piece you need to decode your body and reach your health goals.  


How does a CGM work?

A CGM is a small device that affixes to your arm or abdomen in order to continuously track your glucose levels throughout the day and night. After a quick and painless insertion process, its sensor wirelessly connects to an app or monitor and transmits nearly real-time glucose levels so you have a consistent stream of readouts. Most CGMs have to be replaced every 14 days.  

Who should use a CGM?

CGMs are great for anyone living with diabetes who needs a simple way to monitor their blood sugar levels throughout the day, but doesn’t want to be bothered with numerous finger pricks. The CGM gives you readings without the hassle, so you’ll be able to track spikes and dips in an effort to keep your diabetes well managed. That said, those with prediabetes or no sign of the condition can still benefit from using a CGM if they want to get a better understanding of how their body regulates sugar and how that impacts their overall health and wellbeing. If you’re curious about how to get your body to perform optimally, a CGM can be a great window in some of the more nuanced parts of health that you can’t get just by stepping on a scale. 

How to choose a CGM device?

A CGM is still a medical device, so you’ll need a prescription to purchase it. When deciding which one to choose, consult with your doctor first about the options that are available to you. uses the Abbott FreeStyle Libre, and you can learn more about January AI’s CGM here.

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