The Lowdown on Continuous Glucose Monitoring (CGM) for Athletes


Medically reviewed by:
Dr. Steve Kim, MD

About Dr. Steve Kim, MD

Physician Advisor

Dr. Kim received his BA in Human Biology at Stanford University, before receiving his M.D. degree (Primary Care Track) from UC Davis School of Medicine in 1989. Dr. Kim completed his Internship & Residency in Family Practice from Glendale Adventist Hospital and is Board-Certified in Family Medicine via the American Board of Family Medicine. He has re-certified multiple times; and is currently Board-Certified through December 2030. He has served as Sr Medical Editor for Healthline, and has held faculty appointments at Stanford & UCSF medical schools. He is also a decorated, retired Flight Surgeon from the US Air Force Reserves.

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Continuous glucose monitoring (CGM) has been used extensively for people with diabetes for many years.

The technology measures blood sugar non-invasively throughout the day, providing real-time, frequent updates on your blood sugar. 

However, more recently, we’ve started seeing a lot of health-conscious people and athletes (without diabetes) using glucose monitor patches to track their glucose levels throughout the day. 

So, what’s up with that? 

Health enthusiasts are using CGMs as a tool to learn more about how their body responds to certain things – everything from what you eat to what activities you do and the timing of everything. These devices can give you the resources to biohack your health, metabolism, energy, and productivity – if you know what to do with it.

But are they worth it for the information they provide?

Table of Contents

A brief overview of using CGMs for Biohacking

What We Like
  • Optimizes metabolic health
  • Provides extreme insight to meet your health goals
  • Gives instant feedback and real-time data
  • Super easy to use
  • Works with your phone for app insight
What We Don't Like
  • Device + membership fees are expensive
  • Doesn’t just give you the solution (although does share suggestions)

So, what is a CGM?

A continuous glucose monitor (CGM) is a device worn on your arm or abdomen that uses a sensor to measure the fluctuations of your glucose (blood sugar) values, 24/7. It tracks using a small needle inserted into the skin or a small sensor inserted just under the skin. 

The data is sent to a receiver (like an app) that displays the readings and other relevant info to help you make more informed decisions about how your body responds to your current lifestyle. 

The device can help you track:

  • Glucose (obviously): Both real-time and levels in response to meals.
  • The best fasting or meal timing for your body
  • the best activity or exercise routine for your body
  • How stress and sleep impact you
  • How your habits and routines are affecting you
NutriSense CGM Device on arm

The “continuous” part of the device is in contrast to standard glucose meters that require a finger prick (and only give a single reading). This has been one of the attractions for people without diabetes – these CGMs can provide MASSIVE levels of health insight that we didn’t have access to before with little to no hassle – even more than a Fitbit, Apple Watch, or Whoop can provide.

Best CGM for fitness and health: Signos vs NutriSense vs Levels

There are a lot of these things out there, what makes one different from the other?

Signos vs NutriSense vs Levels

Signos logo 240x60 brand logo 240x60 brand logo 240x60
CGM device used?Dexcom G6 CGMFreeStyle Libre CGM (original)FreeStyle Libre CGM
Dexcom G6 CGM
Initial Pricing1 month plan: $3991 month plan: $399$398 for first month
Subscription pricing?3 month plan: $199/mo

6 month plan: $159/mo
3 month plan: $299/mo

6 month plan: $250/mo

12 month plan: $225/mo

+ annual membership: $199/year
What does subscription price include?-Access to app
-CGM delivery for duration of subscription
-Telehealth assessment
-Weight loss insight
-Access to in-app nutritionist (except 1-month plan)
-CGM delivery for duration of program
-Access to app
-Access to private community (FB)
-1 month (optional) dietitian coaching
-Meal, sleep, exercise, and stress tracking
-CGM delivery for duration of program
-Access to app
-Access to private community (FB)
-1:1 nutrition coaching
In-house dietitian or nutritionist?🟡 not on 1-month plan
Compatible with other fitness trackers?✔ Apple watch✔ Apple watch, Oura, Garmin, Fitbit❌ can only import other health app data
Waterproof?✔ Up to 8 feet❌ Water-resistant up to 3 feet❌ Water-resistant up to 3 feet
Is there an app?
Accepts health insurance?
Free device shipping?

How do CGMs work?

Glucose levels can be affected by what and when you eat, your level of exercise, stress, and even sleep. Why? Because everything is connected – metabolism is one extensive system that relies on many different processes working together. If one link in the chain is disturbed, other systems will be affected.

Today’s modern CGM devices allow you to track your glucose levels, heart rate, sleep patterns, and much more in real time. The technology has progressed so much that the companion apps can even make recommendations to optimize your health and overall athletic performance. They can advise when, what, and how much to eat, exercise, sleep, and more.

The goal is that by following these recommendations; you’ll be able to make tangible improvements in your overall health and well-being.

Surprising things CGMs can tell you

    • How unique you are: Users have worn the same device at the same time as their friend, spouse, or the private communities offered through subscription and had completely different responses to identical meals or stimuli. Finding success in glucose stabilization is not a one-size-fits-all approach!
    • What kinds of carbs are best for you: Carbs have the biggest influence on blood sugar, but when and what kind of carbs you eat can differ. Some people’s blood sugar spiked with rice or oatmeal, while others didn’t budge – the same goes for complex vs simple carbs.
    • How alcohol affects you: We all know that drinking isn’t good for us (especially in the long term), but every person is affected differently. CGMs can show specifically how your alcohol intake impacts your blood sugar and what kind of alcohol may have the longest effects on it.
    • Stress and mood predictions: Stress can cause blood sugar spikes, and steady glucose variability (fewer fluctuations) correlates with a happy mind or better mood.
    • Sleep pattern predictions: Depending on the person, you can watch your trends and compare them to how well you sleep. Some users have noticed certain levels before bed usually result in a deeper sleep.

Levels Health CGM instant feedback data:

Are CGMs legit?

You already track everything – sleep, steps, calories burned, you name it. Why get another tracker? 

The short answer is that a CGM can provide info about your body that you can’t find anywhere else, and brands like Signos can take it to a new level with insight and coaching on how to control your glucose and maintain a healthy lifestyle. 

Some of the suggestions, however, should be considered by fitting into your lifestyle, not basing your life off your glucose spikes and data (aka, don’t get obsessed with it).

To sum up great advice from some NutriSense users…

The apps are incredible for learning about your glucose response to different foods, but being obsessed with the glucose spikes at the expense of a healthy and rich diet is not the answer. Try a variety of food and activities to see how your body responds, while focusing on maintaining a balanced lifestyle. 

The monitor will still help you find the foods that affect you the most that should be cut out and the activities you should be doing, but in a much more maintainable way. You don’t want to burn out, after all.

The benefits of CGMs and who should consider using one

Let’s be honest… most of us aren’t the college kids we used to be. We can’t just eat whatever we want, drink alcohol with (seemingly) no repercussions, or pull all-nighters and still feel fine.

We know what we should be doing to be at peak performance, and there are plenty of resources and devices out there to track our health. However, CGMs arguably provide the most insight possible into our body’s responses to stimuli and our lifestyle and daily choices. 

Anybody can use a CGM, diabetes or not. Many could especially benefit from the data, including people who:

  • Want to prevent future health issues: If you’re at risk of developing type 2 diabetes or want to ward off chronic diseases (like cardiovascular disease and cancer), tracking blood sugar fluctuations can provide insight into what keeps your levels stable to maximize long-term overall health.
  • Have PCOS: In the same vein, because PCOS (polycystic ovary syndrome) is associated with insulin resistance, people with this condition use CGMs to monitor blood sugar over time to avoid issues like type-2 diabetes. 
  • Follow a particular diet: The keto, paleo, low-carb, and carnivore diet communities tend to be concerned about the effects of sugar and carbs (and the blood sugar spikes that accompany them) on their health and productivity. Some use CGMs to keep a closer eye on how their blood sugar levels change and the effects that these changes cause.
  • Intermittent fast: Fasting works for some but doesn’t work for others, according to blood sugar reactions. CGMs can help you find out if you are doing your body a favor or not and what food or time is best for you to break the fast.
  • “Biohack”: If you’re interested in maximizing productivity and want to see how changes in blood sugar affect your ability to get things done, your mood, your energy, etc., CGMs can give you this information.

Who should NOT use a CGM?

Full transparency, based on our research and scouring of the internet, we don’t in good faith recommend CGMs to anyone who is experiencing or has suffered from an eating disorder or is already restrictive with their diet.

Many people have mentioned that consuming virtually any carb can lead to spikes in blood sugar. We’ve seen comments like “should I just go carnivore?”, “do I have to go keto??”, and “should I just not eat at all!?” – NO! You should do what feels best for you, and if having a device like this would make you lose track of your own self-awareness in favor of the numbers, we’d recommend an alternate route like fitness wearables instead.

Which CGM is right for me?

Here’s some more info on the brands mentioned in the chart above.

Signos: Overview

Signos highlights

  • Most consolidated features
  • Best advice for weight loss
  • Only device that you can swim with (up to 8 feet)

Signos combines CGM and artificial intelligence to help you reach your health and weight loss goals.

One of the most difficult hurdles with CGM devices is knowing what to do with the information you’ve gathered. Signos helps this by taking the data from your CGM device and combining it with your own input (food, sleep, activity) to provide actual advice on how to lower your glucose.

These behavior modification prompts help keep you on track, and many users have noted the recommendations as being sustainable and easy to implement.

Signos customer reviews

Online users have great things to say about Signos, especially after multiple app and user interface updates in 2023. Many have lost weight over time, even if that wasn’t their initial goal, and people are excited about the insights that they’ve gathered about themselves.

Outstanding app!Reddit r/Biohackers
Read More
“The Signos app is pretty outstanding… You can see visually where your glucose was when you ate, when you exercise, and when you sleep… it customizes a target range for you based on your glucose tolerance test.”
Genuinely feel 10 years youngerApple app store
Read More
“Now in my third month, workouts come easy… I have more energy than I did 10 years ago… I eat more, and somehow I’m still losing weight… My anxiety is what I would consider a healthy one. I don’t take naps anymore. And I’m genuinely happier. I didn’t know much about metabolic health before Signos.”
Loving the suggestionsApple app store
Read More
“I had no idea how sensitive I was to simple carbs. One cup of white rice made my glucose spike as high as 50g of sugar! I have learned how to make small adjustments and I can now keep my energy constant throughout the day. I’ve slowly but surely lost 8 lbs. Really great tool and experience.”

NutriSense: Overview

NutriSense highlights

  • Registered dietitian access
  • Best for those tracking macros already
  • Most fitness tracker compatibility

NutriSense offers a more personalized approach to their CGM device and program with dietitian coaching. In addition to all the insights provided through the device combined with the app, your Nutrisense dietitian can help you:

  • Interpret and analyze your data: The initial data and info can be confusing, so your dietitian can help explain to hit the ground running
  • Optimize your diet: Help ID the foods that fluctuate your glucose levels and find strategies or tailored meal suggestions
  • Perform better: Help determine the best exercise routine for you and how to fuel it for better metabolic health
  • Create better habits: Guidance in forming lifestyles and routines that are attainable, healthy, balanced and can be maintained for life

NutriSense customer reviews

NutriSense has been around the longest out of the competitors, so they’ve been able to incorporate customer feedback into the app and CGM itself for longer.

Apple App store: 4.6 star | 1.5k reviews

**NOTE: We’ve read through countless reviews, and the biggest issue we’ve seen with NutriSense is customer service. The subscription is not cheap, so be sure to read the fine print (any recurring subscription info) before ordering. 

Great app interface & dietitian experienceApple app store
Read More
“The dietitian is knowledgable and not pushy at all… I can learn to eat my meals at the right time and right order, no naked carbs or carb-rich breakfasts anymore. More sensible than anything I’ve seen so far, and the immediate feedback is an awesome teacher.”
More consistent sleepApple app store
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“I’ve been really impressed by the things I learned. Biggest surprise for me was how well my glucose correlates with sleep quality [tracked with a fitness watch]. I was able to adjust my diet and my sleep became more consistent. Highly recommend, even if it’s just for a few months to gain new insight.”
Unexpected knowledgeApple app store
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“I’ve been using the app for a couple of months and have learned a lot about my glucose response to different foods… The monitor has helped me with cutting out foods that are definitely bad such as processed sugary snacks, and has opened my eyes to the benefits of post-meal walks and fasting.”

Levels: Overview

Levels highlights

  • Most cost-effective
  • More simple app interface
  • Can support 2 kinds of CGM sensors

If you’re new to CGMs, you might not know that most devices use one of two sensors – the Freestyle Libre and the Dexcom G6. Levels is unique because they are the only brand to support both, making them accessible for athletes or health enthusiasts without diabetes like you and me.

Levels Health is the least expensive option for month-to-month access, which is a great route if you’re not yet sure how invested you are in tracking your glucose. The app is straightforward, letting you input just text instead of macros or in-depth data (great if you’re not tracking macros, etc. already).

One issue we ran into – the app does not automatically connect to your fitness tracker, but you can import data from Apple Health or Google Fit. 

Levels customer reviews

Recommended for my clientsApple app store
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“As a Nutritionist, I tried Levels so that I could refer my clients… After months of trial, I was able to fine tune my already healthy diet to boost my mood, energy, sleep, hormones, and weight loss. Now all my clients use Levels when we start a program together.”
Impactful health appApple app store
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“I’ve been using the app for about 6 weeks and find it even more helpful than I had expected… It’s easy to navigate, gives timely and relevant info in a way that’s easy to consume, and has opened my eyes to my metabolic function.”
The best health investmentApple app store
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“I’ve been using Levels since the beta program, it was life-changing. I discovered foods and drinks I thought were “healthy” were contributing to my own metabolic dysfunction… Levels is one of several personalized medicine tools I use… I am in my early 50’s and fell better than I have since I was in my 20s.”

tl;dr - Are continuous glucose monitors worth it for athletes?

If you’re interested in learning how your body is affected by everything you do, a CGM device like those from Levels, Signos, or Nutrisense are incredible tools. They can help you optimize your readings for peak performance and health longevity.

But what if you’re already very healthy, active, and aware of what impacts your body, including your diet, sleep, and activity? Is it worth it for yet another tracking device?

To sum it up, a yearly routine blood test or wearable fitness tracker only shows part of how your body responds to your habits and daily activity. Neither of those offers a full understanding of how different lifestyle choices affect your blood sugar over time and whether your trends are healthy. 

CGMs provide a 24/7 tracking of your glucose levels and, therefore, can show real, in-depth trends and help identify any red flags over time. Even just three months of tracking can provide massive insight into exactly what is being impacted and what you can do to improve it.

Whether you’re looking for short-term improvements like optimizing your training, sleep performance, and nutrition, or you want to maintain long-term metabolic health, CGMs could be your answer to a whole new level of health insights, even if just for a few months.

Our Recommendations

👉 Check out Signos for the most actionable weight loss suggestions

👉 Consider NutriSense if you want personalized dietitian suggestions on top of the traditional CGM program

👉 Go with Levels for the lowest overall cost

CGM for athletes FAQs

Are CGMs safe for non-diabetics?

The technology is still new, but there hasn’t been any evidence to suggest that CGMs are harmful to anyone, including those without diabetes.

Do I need to monitor my blood sugar if I don’t have diabetes?

Short answer – no, people with diabetes should be tracking their blood sugar, but it’s not necessary for non-diabetic people.

The body is more complicated than we think – blood sugar levels don’t exactly correlate with energy levels. So, while CGMs are great for TONS of insight, other factors like hormones, sleep, hydration, caffeine, and more can contribute to feelings of less energy. 

Regularly checking an app to see how your blood sugar changes might not yield the kind of hard-hitting data you’re hoping for. But CGMs are a great additional tool to what you might already be using, and they provide lots of information about your trends over time (helping with longevity and later health problems!).

How long should I use a CGM?

LevelsSignos, and Nutrisense all offer subscriptions ranging from 1 month to 1 year. Depending on your current health or goals with using a CGM, the answer can differ.

If you’re intentionally trying to lower your glucose levels for health reasons, lose weight, or make drastic lifestyle changes, it’s recommended to use a CGM for longer, until you have a better understanding of how to reach your goals.

If you’re just trying it out for the first time and are curious about the data you can uncover, many people have found that they feel empowered enough with the information that they can gather in a month, but it’s recommended to watch your trends for at least 3 months for the optimal insight. 

Think about your year: most of us have months of complete “health” and then months where we can’t remember the last time we cooked at home because we’re so busy (holidays, don’t even get me started…). My advice? Go for the 3 months and see how it goes.