Swim, bike, run: the three disciplines of a triathlon. But how ‘bout this: There’s actually a fourth in the race that can make the difference between a PR and a DNF.

It’s not your training. It’s not your gear. It’s fueling. And it makes a big difference.

In this article, we’re talking all things continuous glucose monitoring and effective fueling for athletic performance. This includes:

  1. The importance of glucose and continuous glucose monitoring (CGM)
  2. What you can learn from your fuel ranges, or Glucose Zones, as an endurance athlete
  3. The importance of stable and sustainable fuel sources and how to find the ones that work for you
  4. How to correlate Glucose Zones with performance outcomes and discover your optimal Glucose Performance Zone
  5. How to maintain your Glucose Performance Zone during an event and how to use CGM to sustain your peak performance

Let’s go.

As athletes, we obsess over every possible metric and variable. Power. Heart Rate. Speed. Sleep. But the one variable we should all be paying attention to? Your fueling. Or, more specifically: Glucose levels. We’ve just never had the technology to actually access that information.

That changes with continuous glucose monitoring (CGM) and real-time glucose visibility.

Using continuous glucose monitoring to get real-time visibility into your glucose levels, you can know how well fueled you are at any given time and when or what you should eat for sustaining peak performance. Glucose is your main source of fuel during intense exercise. It can make or break you. So if there was a way to gauge it’s level at during any given moment, you better believe this insight can make a huge difference.


Simple math here:

Carbohydrate = glucose. Optimal levels of glucose = optimal levels of performance.

The energy generated from carbohydrates is available much faster than that from fat. It’s no question – in both scientific and athletic communities – that glucose is your preferential fuel during moderate to intense activities.

Eating carbs during exercise improves endurance. At this point, that’s dogma. And the evidence behind it is substantial. So it's no doubt then that carbohydrate feeding has a key role in providing the energy to perform work and to sustain endurance performance.

Although there are a few exceptions to the rule, such as fat-adapted or ketogenic training, carbohydrate feeding has been the fueling foundation for endurance athletes.

But it's time to change the way you carbohydrate.

Think about it this way: It doesn't matter if you’re working with a Ferrari SF70H or a commercial Honda Civic—they both go the same speed if there’s no fuel in the tank.

The right type of fuel is also needed, and at the right time. You can't put low octane fuel in a race car, and you definitely better not wait until the car is running on fumes to refuel. Eventually, the car will roll to a stop and the engine may need to be serviced before the next race.

The takeaway: Driving (or pushing your limits) on empty is never a good idea.

To take this car analogy further, when you’re driving on the track, you simply keep an eye on the fuel gauge and turn off the track when you see that you need to refuel. But on the trail, as an athlete, you get used to just guessing at your fuel levels based on feeling.

Meet the Abbott Libre Sense Glucose Sport Biosensor: The first continuous glucose monitor adapted for athletic performance.

With this biosensor, there’s no more guessing.

Let's use that race car analogy one more time: If you spend a lot of time and resources under the hood of your Formula One Ferrari, you can’t then skimp on the way you fuel the car, right?

It’s the same with your body. You can train all you want, but if your fueling is off, what’s the point?

With the biosensor on your arm, you’ll be able to track multiple glucose-related data points on the Supersapiens app. One of the most important for in-competition performance? Your feel and performance in different glucose ranges.

Your optimal fuel range will vary based on your individual body, the type of activity, and the type of adaptation you are seeking.

After monitoring your glucose data with the Supersapiens app for a little while, you'll be able to determine your optimal fuel range—your Glucose Performance Zone. Training or racing outside of your Glucose Performance Zone may negatively impact athletic performance.

Essentially, we’re turning the guessing game of fueling and energy management into your personal science. With the Supersapiens app connected to the Abbott Libre Sense Glucose Sport Biosensor, you’ll know your body’s individual response to glucose. With real-time visibility, you're able to make real-time adjustments. Boom. Personal records all around.


Eat a banana. See immediately how your body reacts to it. From this, you can discover which foods provide the most stable and sustainable energy. (Hint: It may or may not be a banana.)

Look at the two graphs below. This is about limiting the steep "spikey" nature of the line on the graph—stable and sustainable (optimal) means relatively flat. The goal would be to find fuel sources that result in the graph on the right.

So you eat a banana. Then you analyze your training sessions. Compare your workouts. Then, fine tune your fueling strategy.

To help discover what foods provide stable and sustainable energy for you, check out our article EXPLAINED: CGM AND THE ENIGMA OF ENERGY MANAGEMENT FOR ATHLETES

How to determine in Training:

  • Plan a training session
  • Create an Exercise Event in the Supersapiens app
  • Analyze your personalized Event Analytics
  • Overlay or compare with other performance data and determine where you were when you felt the best and where you felt the worst: what glucose fuel range were you in?
  • Dial in your Glucose Performance Zone


CGM Data Analysis from Supersapiens app
Data Analytics in the app

Once you've discovered your Glucose Performance Zone, you need to maintain it throughout competition to sustain your peak performance.

How do you use these insights in a race?

Simple: Monitor your glucose levels and maintain your Glucose Performance Zone. It’s all made a bit easier with real-time visibility to your Live Glucose Reading and Trend Arrow.

While there are basic guidelines for when and how much to consume during any particular activity—such as 60-90 grams of carbohydrates per hour or about 250-350 calories—the optimal timing of when to eat to ensure glucose stability, maintain optimal fuel levels, and sustain peak performance on an individual basis has been a bit of a black box.

It’s different for every body.

So it should be no surprise that managing your optimal fuel levels is nearly impossible without real-time visibility to your own glucose levels. With your Live Glucose Reading and Trend Arrow, you not only know where your fuel levels are right now, but also where they're headed. And you can make real-time fueling adjustments accordingly.

In other words, with a quick glance, you can see your Live Glucose Reading and Trend Arrow, and know if you need to eat now or not.

Here’s an example: Let’s say in training, you determine that your Glucose Performance Zone is 120-139 mg/dL—that’s your optimal fuel range, the zone you want to keep your glucose levels at all times during training or competition. We call it your GPZ.

If your Live Glucose Reading is at the lower bound of your Glucose Performance Zone, say 120 mg/dL, and your Trend Arrow is aimed straight up (indicating that your fuel levels are rising quickly) then you know that you do not need to refuel right now because your glucose levels are likely headed back into your GPZ.

Note: As discussed in our article, GLUCOSE: HOW CGM IS REVOLUTIONIZING SPORTS, there are many factors that impact your glucose levels. For example, you may see your levels temporarily increase without additional fuel intake due to an adrenaline or other hormone-induced glucose response.

Live Glucose Reading at the lower bound of your Glucose Performance Zone? Say 120 mg/dL and your Trend Arrow is aimed straight down? (indicating that your fuel levels are dropping quickly) Then your fuel levels are dropping. And you know you need to refuel because your glucose is headed out of your GPZ.

Got it?

So, in short:

  • With CGM, in-race fueling and energy management no longer need to be a guessing game.
  • Now you can find out and be confident knowing exactly what foods provide your body its most stable and sustainable glucose rise, keeping you within your optimal fuel range at all times.
  • With your biosensor on, correlate your Glucose Zones with performance outcomes and determine your Glucose Performance Zone.
  • Forget guessing when to refuel. Now, glance at your Live Glucose Reading and Trend Arrow direction, and know whether or not to refuel.

No more guessing. No more missed opportunities.


For more information on Supersapiens and stories from our athletes, follow us on Facebook, Instagram, and Twitter: @supersapiensinc


  1. Hearris, M. A, et.al. Regulation of muscle glycogen metabolism during exercise: Implications for endurance performance and training adaptations. Nutrients, 2018;10(3), 1–21.
  2. Jeukendrup, A. E., Raben, A., Gijsen, A., Stegen, J. H. C. H., Brouns, F., Saris, W. H. M., & Wagenmakers, A. J. M. Glucose kinetics during prolonged exercise in highly trained human subjects: Effect of glucose ingestion. Journal of Physiology, 1999;515(2), 579–589.
  3. Katch FI. Sport and exercise nutrition. 4th ed. Baltimore, MD: Lippincott Williams & Wilkins, 201
  4. O'Brien, M, et.al. Carbohydrate dependence during marathon running. Med Sci Sports Exerc, 1993;25**,** 1009-17.
  5. Marliss, E. B. and M. Vranic. 2002. Intense exercise has unique effects on both insulin release and its roles in glucoregulation, implications for diabetes.
  6. Volek et al. Metabolic characteristics of keto-adapted ultra-endurance runners, Metabolism, Clinical and Experimental, 65:100-110, https://pubmed.ncbi.nlm.nih.gov/26892521/