Due to rising interest in well-being, health tech has been making fast strides in the industry. Worn daily, a continuous glucose monitor (CGM) tracks glucose, helping users to make better choices.

CGMs were first made for people with diabetes. Now, they’re sold over the counter and are used by anyone who wants to understand how their body reacts to food, movement, and stress.

This guide breaks down how CGMs function and the benefits they offer for your health and wellness.

About CGMs

Continuous Glucose Monitors (CGMs) can always track your blood sugar. A CGM uses a small sensor placed under the skin to check your cellular fluid for glucose.

You’ll usually wear the sensor on your upper arm, though some use the belly area. It sends glucose data to a receiver or phone app, giving live daily updates.

Because they measure glucose every minute, CGMs alert you to glucose changes when you eat, walk, or feel nervous.

This information helps you realize how your habits affect your system and makes it easier to assess your overall health.

History of CGMs

In June 1999, the FDA approved the first CGM device made by Medtronic MiniMed. This early version was for short-term use—up to 72 hours—and users couldn’t view the data themselves. Only doctors could access it during checkups.

In March 2001, the FDA approved the Glucowatch Biographer by Cygnus, Inc. It was the first real-time CGM that didn’t involve a needle stick. Worn like a wristwatch, it pulled glucose from under the skin using a mild electric current. Though non-invasive, it caused skin irritation due to the method used to draw fluid.

Medtronic came out with the Guardian REAL-Time CGM in 2004. This version included alerts for low or high glucose. In 2006, Medtronic brought out a CGM that could be linked to an insulin pump. The company launched the STS system in 2006 which could only be used for three days. They later launched the G4 Platinum in 2012, followed by the G5 Mobile in 2015. The G5 could send data straight to a smartphone.

Abbott released its FreeStyle Navigator in 2008. Around the same time, Medtronic unveiled the iPro, a professional CGM system. In 2009, Medtronic released a more advanced version of its previous integrated CGM.

The Enlite sensor, introduced in 2013 by Medtronic, could pause insulin delivery when glucose dropped too low. It worked with the MiniMed 530G system. In 2017, the first hybrid closed-loop system began with the release of Medtronic’s Guardian Sensor 3.

How Does A Continuous Glucose Monitor (CGM) Work?

Various CGMs are currently on the market, but they are all based on the same core process. CGMs come with three main parts:

Sensor

The CGMS can measure your glucose levels in the fluid under your skin. You inject the device into your skin with a needle. After the needle comes out, the sensor gets left in your arm. Depending on which brand you choose, your sensor should last from 7 to 15 days. In some cases, your healthcare provider will leave specialized sensors in place for a few months.

Transmitter

After calculating your glucose level, the sensor sends it wirelessly to your chosen device. Some CGMs offer the possibility of using the transmitter a second time by simply changing the sensor. In other situations, it comes attached to the sensor and gets discarded with it.

Smartphone App, Receiver, or Insulin Pump

You’ll see your current glucose levels and a chart of your past readings on one of these tools. It also shows whether your levels are going up or down. Most CGMs work with smartphone apps, but some also come with their own handheld readers. Some CGMs connect with insulin pumps and send data to them directly.

Here’s a step-by-step breakdown of how CGMs generally work:

• You place the sensor under your skin, usually on your belly or arm. The device that does this makes it quick and simple. A sticky patch keeps the sensor attached to your skin.
• The transmitter either clips onto the sensor or is already attached. Some transmitters need charging before use. You can add extra tape if needed to help everything stay in place.
• Once inserted, the sensor needs time to start working. This warm-up time can last anywhere from 30 minutes to 2 hours.
• Most CGMs begin sending readings automatically after the warm-up. Some, however, need a fingerstick blood test to calibrate them before they show any data.
• You’ll then be able to see your glucose level in real time on your app, reader, or insulin pump. You may also get alerts when your readings are outside the expected range. Different people may find different ranges for blood sugar to be healthy.
• If the sensor isn’t working any more, you will need to insert another one, so the process can continue.
• You have the option to get your glucose data on your computer to notice trends in your blood sugar. Certain CGMs constantly transmit this data to your healthcare team, so it’s easier to watch your progress.

What Are The Benefits Of CGMs?

People with diabetes used to rely on fingerstick tests. CGMs have made glucose tracking easier and more detailed.

• Round-the-Clock Blood Sugar Tracking: CGMs monitor your glucose levels all day and night. They work while you eat and while you sleep, showing you how your daily choices affect your blood sugar patterns.
• Time In Range Analysis: This feature counts the time your glucose stays at healthy levels. It also shows when your numbers get too high or drop too low, giving you a complete picture of how steady your glucose stay throughout the day.
• Safety Features: Doctor-prescribed CGMs warn you when glucose levels become dangerous. They sound alarms for high, low, or fast changes. These warnings help prevent serious problems when people don’t notice changes, when they sleep, or when they drive.
• Data Sharing: People using CGMs can send their glucose information to family or medical teams.
• Remote Monitoring: Other people can check glucose levels from far away. Parents or caregivers use this feature to help. This works really well for kids with type 1 diabetes or elderly people who need support managing their blood sugar.
  

Who Can Benefit from CGM?

CGM started as a tool mainly for diabetes patients. Today, many different types of people find it useful for health tracking:

• People with Diabetes: CGM helps you better control your blood sugar levels. It reduces the chance of health problems and makes managing diabetes easier.
• People with Prediabetes: Spot changes in blood sugar that might show early diabetes signs. Take action now to stop full diabetes from developing.
• Weight Management: Learn how different foods affect your blood sugar and insulin. This will help you create a weight loss plan that is better for your body.
• Athletes and Fitness Enthusiasts: Improve your training by observing how workouts affect blood sugar. Then, adjust what you eat based on this information.

What Affects the Data from CGMs?

Food choices have the biggest impact on blood sugar. But several other things can change glucose numbers too.

• Stress chemicals in your body can make blood glucose go higher. Cortisol is one example that pushes blood sugar up by telling your body to release stored glucose.
• How much you sleep changes how your body handles glucose. Bad sleep messes up your body’s processes and raises cortisol, leading to uneven glucose numbers.
• Working out makes blood sugar drop because your muscles use insulin better. You might also see blood sugar go up after very hard exercise. This happens because intense workouts temporarily raise stress chemicals.

Conclusion

CGMs give you a strong tool to learn about your body’s glucose and make smart health choices. Maybe you want to eat better for your health, or you’re an athlete who wants better performance. CGMs give you useful information to reach your goals.

Using CGMs along with advice from health experts helps you create health plans made just for you. These plans can improve your health for many years. This knowledge helps you feel confident about making good changes that last.

FAQs

Is CGM Helpful For People With Type 2 Diabetes Who Are Not On Insulin?

Yes! Since ADA 2025, CGM is recommended for Type 2 diabetes patients using insulin and other medicines to lower blood sugars.

How Do CGM Alerts Help In Diabetes Management?

Users can act quickly to manage their sugar levels because they are warned by CGM alerts for changing and extreme highs or lows. Personalizing alerts helps nurses pay attention to important information and avoid being tired of constant alarms.

What Are The Latest ADA 2025 Standard Of Care Guidelines On CGM Use?

The newest ADA SOC 2025 tells us that CGM should be used by anyone with Type 1 diabetes and those taking insulin for Type 2 diabetes. Doctors also usually recommend it for pregnant people, older adults at risk for low blood sugar and children at the time of diagnosis.

Evelyn Brown