What is a continuous glucose monitor and how can it help you?

A continuous glucose monitor is a wearable device that measures blood sugar, or glucose. Because it is attached to your body, it takes measurements throughout the day and night, and you can view the results on a device, such as a smartphone.

Continuous glucose monitors (CGMs) were developed for people with diabetes to help them monitor and manage changes in blood sugar levels. 

However, continuously monitoring your blood sugar can provide helpful information even if you don’t have diabetes. For instance, it can tell you how your blood sugar levels respond to different foods.

ZOE runs the largest nutrition science study in the world. Our data shows that everyone responds differently to food, and blood sugar responses can vary greatly from person to person, even when they eat the same food.

These responses are meaningful because, over time, exaggerated post-meal blood sugar responses can increase your risk of developing chronic diseases, including type 2 diabetes. 

The ZOE at-home test includes a CGM to test your blood sugar responses to foods, if you opt to take part in our research program. We also measure your blood fat responses and provide detailed insight into your gut microbiome, which is linked to your overall health.

From this information, the ZOE program can help you find the best foods for your body so you can reach your long-term goals. 

You can take a free quiz to see how ZOE can help you.

How does a continuous glucose monitor work?

A CGM measures your blood sugar around the clock. 

You typically wear the monitor on your upper arm or stomach. It stays on at all times, including during a shower or while you sleep.

Using a small sensor inserted under the skin, the monitor measures how much sugar is in the fluid surrounding your cells. It takes a measurement every few minutes.

Then, depending on the type of monitor you're using, the results are sent to your phone, insulin pump, or some other device for easy tracking.

There are several different CGM devices available, with different battery lifetimes. Some products last 2 weeks and others up to 3 months before the battery runs out. 

Who can use a CGM, and how do you get one?

A doctor may prescribe a continuous glucose monitor for people with type 1 diabetes and some people with type 2 diabetes. 

These monitors can be helpful for people who are unaware that their blood sugar is too low, which is called hypoglycemia. This includes young children and some older adults.

It also includes people who regularly have hypoglycemia and no longer feel the typical warning signs.

Doctors may also prescribe a continuous glucose monitor if you regularly have high or low blood sugar levels, or if you are on intensive insulin therapy.

Certain types of monitors can be paired with an insulin pump as part of a closed-loop system. 

With these devices, if the monitor detects that your blood sugar levels are outside your target range, it communicates with your insulin pump. The pump then delivers the right amount of insulin directly into your body. Some people call this device an artificial pancreas.

Evidence suggests that this technology can improve the quality of life for people with type 1 diabetes.

But anyone can use a continuous glucose monitor as a tool to better understand their blood sugar levels, which can impact many aspects of their overall health. 

In the U.S., continuous glucose monitors are typically only available on prescription.

But the ZOE at-home testing kit includes a CGM for most people who opt to take part in our research program, depending on location and health status. 

We use CGM data alongside other test information to help you find the best foods for your body.

Health benefits of tracking your blood glucose

Continuous glucose monitors can be useful for people with diabetes who need to monitor their blood sugar levels. For those without the condition, using a CGM can provide insights into how blood sugar levels change after eating and an opportunity to make changes to their diet and lifestyle.

People with diabetes

If you have type 1 or type 2 diabetes, evidence suggests that using a continuous glucose monitor can help you better control your blood sugar, especially if you have a high risk of hypoglycemia.

Since these monitors measure your blood sugar continuously, you can read your levels in real time, which can help you adjust your food intake, medicine, or activity level as needed. 

Some monitors even have an alarm option that will alert you or a loved one if your glucose levels are too low or too high. 

Because CGMs measure glucose in the space between the cells in your tissue, rather than directly in your blood, the readings will be slightly different to a finger prick test. And you may see a time lag in your glucose response. 

Before adjusting your medication, make sure to confirm any results with a finger prick test.

People without diabetes

Using a continuous glucose monitor can be helpful even if you don’t have diabetes. 

ZOE’s groundbreaking research shows that CGMs can be a useful tool in personalized nutrition, as they accurately show how blood sugar changes after food. This paves the way for our ZOE members to understand how their blood sugar responds to the foods they eat.

This is important because it can impact your overall health.

After you eat, your body breaks down the carbohydrates in your food into glucose, or sugar. This sugar enters your blood, causing blood sugar levels to rise. From there, it is transported to your cells to use for energy or to store for later. 

As your cells take in the sugar, the amount in your blood goes down. This rise and fall in blood sugar is normal, but frequently large blood sugar spikes and crashes can impact your health.

Over time, it can increase the risk of type 2 diabetes, heart disease, and weight gain.

ZOE scientists run the largest study in the world investigating postprandial glucose — how blood sugar levels change after you eat or drink — with over 20,000 participants so far.

Our data show that everyone’s blood sugar responses to foods are different. Even identical twins can have very different responses. 

If you’re interested in understanding how your body responds to the food that you eat, and how you can harness this knowledge to find the best foods for you, then looking at your blood sugar is an important piece of the puzzle. 

Understanding your personal responses to food

Our research shows that in addition to your blood sugar levels, your blood fat responses and your gut microbiome also play decisive roles in what happens to your body after you eat. 

There are trillions of microorganisms living in your gut, collectively called your gut microbiome. These microbes are essential not just for your digestion, but also for your immune system and your overall health. 

ZOE scientists have identified 15 “good” bugs and 15 “bad” bugs that are linked to your health. 

The good bugs are associated with heart health and good metabolic responses, while the bad bugs are linked with a higher risk of heart disease, type 2 diabetes, inflammation, and belly fat.

The ZOE at-home test analyzes your blood sugar and your blood fat responses, as well as the makeup of your gut microbiome, to give you a full picture of how your body responds to different foods.

With the ZOE program, you receive personalized food recommendations based on these tests to help you eat the best foods for your long-term health goals and allow your gut microbes to thrive. 

You can take a free quiz to see how ZOE can help you.


A continuous glucose monitor is a device that you wear around the clock to monitor your blood sugar levels. It takes measurements every few minutes. For people with diabetes, this can help keep blood sugar levels in the target range. 

Those without diabetes can also benefit from continuously monitoring their blood sugar levels. Learning how your blood sugar responds to different foods and combinations of foods can help you avoid large spikes and crashes in blood sugar.

Over time, large changes in blood sugar levels can increase the risk of heart disease and metabolic diseases, such as type 2 diabetes. 

Learn how ZOE can help you discover the best foods for your body and your long-term health.


Artificial pancreas. (2021). https://www.niddk.nih.gov/health-information/diabetes/overview/managing-diabetes/artificial-pancreas

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