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September 11, 2020

How To Get Started Using a CGM

Sensors, transmitters, readers...there's a lot to understand about Continuous Glucose Monitors. Let us take you through the components, their functions, and how to get the most out of your CGM.

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A How-To Guide for Using a CGM

Home / Living with Diabetes / How To Get Started Using a CGM

You’re ready to start using your CGM. You and your doctor have decided that you should try a CGM, and you’ve done all this research about which supplier and type of CGM to purchase, but perhaps you don’t know what to do now that you have received your new CGM. Well, let’s take it out of the box and learn more.

Here’s your how-to guide to get started using your CGM. This article will help you understand the components of your CGM and how to use them for the safest results. 

What is a continuous glucose monitor? 

In this piece, we’ll be directly addressing questions for users who have already purchased their CGM, so we’re going to assume you know what one is. If you’re looking for more basic information, or wondering, “Should I get a CGM?,” don’t worry, US MED has you covered! Check out this article for more information. 

However, as a quick reminder, let’s go over some CGM basics. CGM stands for continuous glucose monitor and is an FDA-approved tool to monitor blood glucose levels. A CGM is comprised of three parts: the sensor, the receiver, and the transmitter. The sensor attaches to your skin and tracks your subcutaneous blood glucose levels over time. The sensors must be changed at regular intervals, with the amount of time you can leave them on your skin varying by brand. The sensor includes a transmitter that sends data to the receiver—often your own smart devices in modern systems—which then displays the information for you. 

Who can use a continuous glucose monitor?

People living with diabetes who regularly monitor their blood sugar and administer insulin (orally, through syringe, or by use of an insulin pump) are candidates for continuous glucose monitoring. More specifically, the Centers for Medicare & Medicaid Services (CMS) have updated their eligibility on continuous glucose monitors to broaden the use of CGMs within the diabetes community.

As of July 2021, the requirement to qualify for a CGM are:

  • Test your blood glucose levels daily
  • Administer insulin at least 3 times a day or be on an insulin pump

Benefits of using a continuous glucose monitor.

Patients living with diabetes who use a Continuous Glucose Monitor have reported that the CGMs are accurate, easier to use than traditional finger-sticking methods, and virtually painless. A continuous glucose monitoring system is a compact testing device that continuously monitors your glucose levels in real time. A sensor on your body allows the system to send real-time readings wirelessly to a monitoring device or an app on your phone that displays your sensor glucose data. You can actually see in real-time the effects of food and exercise on your glucose levels! It can warn you of cases of hyperglycemia, which is when your sugar is too high, or hypoglycemia which is when your sugar is too low. And you can see these as they happen, by interpreting the trending arrows, avoiding potentially dangerous consequences. This is a major breakthrough over traditional “static” blood glucose monitoring, which only provided one reading at a time.

And here’s the part people love: CGMs can virtually eliminate the need for regular, painful fingerstick testing*, which has been the only way to personally check your glucose levels.

Your new CGM system can also help you identify long-term trends in your glucose levels. These trends often go undetected by those who depend on traditional blood glucose meters. Understanding how your lifestyle impacts glucose levels is so important and a CGM will document those trends giving you valuable information on changes in levels while you’re sleeping, changes in trends between meals, as well as during and after physical activity.

But, they have to be used correctly for you to receive these benefits. 

So, let’s get started using our CGMs!

How to use a continuous glucose monitor.

FreeStyle-Libre-continuous-glucose-monitorTo get started, we’ll talk about the components of the CGM and how you’ll use them. The sensor is the trickiest part of a CGM system to get right. The transmitter is included in the sensor, so you do not have to fiddle with it at all. And, modern CGM systems all connect the receiver to  your Smartphone or tablet. With most systems, you will not have to carry around a pager-like device to read your blood glucose data. 

When you receive your CGM make sure to completely read its user guide. Every system will be slightly different. Although the steps will be relatively similar, you should check the order laid out here against your device’s requirements. 

For the purposes of streamlining, the steps listed below are for the Freestyle Libre system. This CGM does not require fingerstick calibration, which makes it extremely easy to use. However, bear in mind that you will likely need to perform some type of fingerstick calibration if you purchase a different CGM. 

Four Steps to Use Your Continuous Glucose Monitor

1. Read the CGM’s Manual 

To get started with the Freestyle Libre, open your package and pull out the reader, sensor pack, and sensor applicator. Make sure that you are familiar with all aspects of these three components. Then charge your reader and prepare to assemble and apply the sensor. 

2. Apply the CGM Sensor 

As mentioned above, applying the sensor is the trickiest part of using a CGM. The sensor for the Freestyle Libre should be attached on the back of your upper arms. Choose an application site that is clean and does not have any skin imperfections. Then clean the site with an alcohol wipe. 

Once your application site is ready to be used, put the sensor in the applicator. The sensor will be completely covered by the applicator—it has a needle, so do not put your finger inside the applicator for any reason. Then put the applicator on the site and press down firmly. Pull the applicator off your arm and gently press the adhesive on the sensor to your skin. 

3. Align the CGM Reader

Now the Freestyle Libre sensor is applied, so it’s time to align it with the reader. Turn the reader on and press the “start new sensor” button. Bring the reader close to the sensor to scan it. Wait twelve hours initially for the reader to calibrate with the sensor. Then you can track your blood glucose as normal. 

4. Monitor Your Levels 

Understanding the data that the reader provides is really the crucial part. Again, using the FreeStyle Libre as an example, here’s a sample of what your reader may display. You’ll be able to set your target glucose range and see how your glucose levels are trending in one display. The sensor’s readings are gathered in the system range of 40-500 milligrams per deciliter (mg/dL) but the whole display range is 0-350 mg/dL for ease of review on screen. That means a glucose reading above 350 mg/dL will show at 350 mg/dL. For readings above 350 mg/dL, a line is displayed at 350 mg/dL.  

The reader will also provide you with your glucose trend arrow to show you the rate at which your levels are trending. E.g., the arrow displayed below means that glucose is falling between 1 and 2 mg/dL per minute.  


Image credit FreeStyle Libre.

Most of the CGM systems on the market will have similar start-up procedures. Clearly, applying the sensor is tricky, but the rest of the process should be user friendly. If you have questions on how to set up your CGM, consult your user manual, healthcare professional, or the customer service line of your CGM supplier. 

Continuous Glucose Monitor Tips and Tricks 

When getting started with your CGM, there are a few tips and tricks to remember so that the process goes smoothly. 

  • Read your user manual before applying anything. This is complex technology and your manual will make sure you’re adhering to manufacturer guidelines. 
  • Always place the sensor on the recommended site. Often a specific area of your body is the only approved site for the CGM and placing the sensor somewhere else can cause inaccurate readings. 
  • Calibrate your CGM system as your user manual describes and on the correct timetable. Whether you need fingerstick calibration or not, this process ensures that your CGM readings remain accurate. 
  • Don’t become too overwhelmed by all the alerts at first. Remember that this device will simplify your blood glucose monitoring and this learning curve is an important time in your life with a CGM. As you learn more about how to manage your blood glucose, the number of alerts will decrease and the ease of your diabetes care will increase. 


CGMs can be a literal lifesaver for someone with blood glucose issues. Whether you have diabetes, hypoglycemia, or another blood sugar condition, you should consider purchasing a CGM. In order to have the best CGM experience possible, it is important that you start the process correctly. Once you understand exactly how to set up and use your CGM, the process will become automatic. But, be prepared for the first couple of sensor applications to take some time. 

In this article, you have learned the start-up process for the Freestyle Libre system and some tips and tricks to help you stay sane as you transition to a CGM. If you still have questions on setting up your CGM, our US MED customer care representatives are happy to help you get off to a great start with your CGM. Contact us today to learn more about our line of CGMs, our simple 90-day CGM supply delivery service, and what we can do for you. 


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