Continuous Glucose Monitoring
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A Starter's Guide to Continuous Glucose Monitoring (CGM)

Having diabetes is a full-time job. You have to monitor your diet, activity, stress levels, sleep along with simultaneously calculating and managing carbohydrate to keep tabs on your blood sugar levels. In this article, we explain what is a CGM and how you can use the data obtained to help you manage and navigate your journey towards diabetes reversal.

What is Glucometer?

Understanding About Glucometer

People with diabetes often need to measure their blood sugar levels in order to maintain their health. To do this, people often use devices like the CGM and glucometers. So what is a glucometer? Simply put, a glucometer is an electronic device that is used to measure blood sugar levels in a person with diabetes. It is by far the most common method used by diabetics for monitoring blood sugar levels. The use of a glucometer calls for you to prick your fingertip and then add a drop of your blood to the device. The glucometer will then analyze your blood to determine your blood sugar levels. Even while this is a common and simple approach to use, having to repeatedly prick your finger during the day may be uncomfortable, tiresome, and a source of irritation. Because the glucometer only displays the blood sugar level at that precise moment, it is very difficult to get an accurate picture of your overall sugar levels with this method. This is only one of the disadvantages of using this method. If you have recently had a meal, a snack, or if you have been hungry for an extended period of time, this will have an effect on the readings of your blood sugar level, which may not end up being totally correct.

What is Continuous Glucose Monitoring (CGM)?

It is a process that continually monitors the glucose (sugar) in your blood through an external device that’s attached to your body, to give real-time updates on your blood glucose patterns and trends. Also know about diabetologist.

What is Blood Glucose Meter (BGM)

About Blood Glucose Meter

Blood Glucose Meters (BGM) measure glucose levels in your blood at a single moment in time and require deliberate action to get a reading,

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Difference between Continuous Glucose Monitor (CGM) & Blood Glucose Meter (BGM)?

                                                               Blood Glucose Meter(BGM)                                                                                                                       Continuous Glucose Meter (CGM)                                                        
A 'Finger-stick Blood Glucose Meter' (BGM) provides a measurement of the blood glucose level at a specific moment in time (when you prick your finger) A CGM typically generates a new glucose level every minute, and records the reading every 15 minutes for a duration of 14 days or 2 weeks.  
                                       BGM is similar to a photograph-providing a  single blood sugar "snapshot"                                                       CGM is like a video - providing a constant stream of information on glucose level, trends and overnight data                

How Does The CGM Device Work?

Another device that is used widely among people with diabetes is the continuous glucose monitoring machine or CGM. So how does CGM work?

Instead of taking a blood sample from the finger, continuous glucose monitoring systems employ a sensor and a reader. Usually on your abdomen or arm, you insert a tiny sensor beneath your skin. This step is fast and simple to do using an applicator. The sensor is held in place by adhesive tape. In the fluid under your skin, the sensor monitors the glucose levels. All day and night, the majority of CGM devices collect readings every five minutes. Depending on the device, you'll need to replace the sensor often. You typically replace sensors for most gadgets at home every 7 to 14 days. Your healthcare practitioner will replace the sensor in a procedure in their office a few times (or fewer) per year for certain long-term implanted CGM systems.

To wirelessly communicate glucose data from the sensor to a device where you may examine it, all CGM systems need a transmitter. The transmitter for certain CGM systems is reusable and fastens to every fresh sensor. The transmitter is a component of the disposable sensor for different CGM systems. Depending on the CGM system, glucose readings from the sensor are sent to an insulin pump, an app on your smartphone, or a portable device called a receiver (similar to a cell phone). Anytime, you may download CGM data (including trends, history, and real-time glucose levels) to a computer. Some CGM systems will continually deliver data and your provider may also get the information. Also know about best sugar test machine in India.

How does the CGM device measure glucose levels?

CGMs measure the body’s glucose levels in real-time by sensing the glucose present in tissue fluid (also called interstitial fluid) through a sensor placed on your skin and transmits those readings to a small recording device called receiver. The CGM device has 3 components: the Sensor, Transmitter, and Receiver.

  • The Sensor consists of a tiny probe that is inserted under the skin of the upper arm using a simple applicator. Once placed, the device continuously records your glucose levels throughout the day/night for a duration of 14 days.
  • The Transmitter sits on top of the sensor and is attached to an electrode that sends glucose information to a separate receiver or a smartphone app.
  • The Receiver displays real-time glucose level, whether blood glucose is trending up or down, and your overall glucose history.
  • AGP Report - The blood glucose reading from the CGM device is then converted into a standardized report called an Ambulatory Glucose Profile Report which gives a detailed picture of your 14 day readings and includes a summary of your glucose profile, daily glucose graphs and the times you measured above and below your target range.

What is an Ambulatory Glucose Profile Report?

Developed by the International Diabetes Center, an Ambulatory Glucose Profile (AGP) report, is a standardized way of reporting continuous glucose monitor (CGM) data. It is a tool that provides a simplified way to look at data on your blood glucose patterns and trends based on at least 7 to 14 days of CGM data.

What are the General & Specific benefits of using a CGM?

  • CGM plays a vital role when it comes to predicting your current level of metabolic fitness thus helps in positively influencing improvement of your future metabolic health.
  • It allows you to keep a real-time check on how your body is functioning by offering you instant metabolic data to make the necessary changes to your lifestyle and reduce the likelihood of a surprise diagnosis later in life.
  • CGMs are particularly useful after meals and overnight, as they record when glucose levels drop or rise below a preset threshold.
  • CGMs provide a good way to monitor time spent “in range” (time spent within a normal, pre-specified blood sugar range) for people that have trouble reaching and maintaining target blood sugar.
  • CGMs are particularly useful if you often have lows and are unaware of when they happen (hypoglycemia unawareness).

How can I use the CGM data to reverse diabetes?

The AGP report allows your healthcare team to assess blood glucose levels, trends and patterns thus helping identify the times of day when glucose levels are consistently low, high, or fluctuating. The general goal for individuals with diabetes is to have glucose levels stay within the target range of 70 to 180 mg/dL for at least 70% of the day, and spending less than 3% of their time in hypoglycemia (under 70 mg/dL). This information from an AGP report helps your doctor set relevant goals for your diabetes management by providing care that's more precise and effective.

Also read about uses and side effects of sugar tablet


At the end of the day any data is meaningless if it cannot be interpreted correctly or not used by a provider to aid in diagnosis and a more focused treatment approach. Remember, CGM is a personal tool and not necessarily a single aspirational target or range that is universal. Your individual goals will depend on your needs, dietary and lifestyle habits, comorbidities and complications. Based on your unique presentation and recorded CGM data, your doctor will educate you on how to interpret and use your data to make the appropriate decisions to achieve your blood sugar goals. Also know about reversing type 2 diabetes.


Is CGM accurate? 

Yes, CGM or continuous glucose monitoring machines are accurate. The tiny sensor within the arm takes the blood sugar reading every 5 minutes 24/7 till the device is worn. The readings are precise and are recorded in real-time. You can also calibrate the readings taken by your CGM with your glucometer to check the accuracy. Know more about best glucometer with glucometer price details

How long does a CGM last?

The sensor device inserted into the body that takes the readings can be worn for 7-14 days. The graph can be downloaded on your phones and laptops and you can use that with your endocrinologist to titrate the insulin doses accordingly.

What is a cgm device?

A glucose monitoring device is an electronic tool or device that measures blood sugar levels in people with diabetes. It comes with a sensor and a reader which needs to be placed under your belly or arm and is held in place by an adhesive tape. It measures blood sugar levels constantly and lets you know whether or not to take insulin.

How does a cgm monitor work?

A CGM works by inserting a small sensor beneath your skin, generally on your abdomen or arm and monitors the blood sugar levels in the body continuously. The data is wirelessly sent to a monitor via a transmitter. The monitor may be a component of an insulin pump or a separate gadget that you carry in your pocket or handbag. The monitor stores and displays the blood sugar readings. 

How does a cgm sensor work?

A CGM comes with two things, a sensor and a reader. A tiny sensor that is usually inserted under the skin on the belly or arm is how a CGM essentially functions. Your interstitial glucose level, or the glucose present in the fluid between your cells, is measured by the sensor. Every few minutes, the sensor measures the glucose and this data is wirelessly transmitted to a monitor.

What is a sugar checking device?

People with diabetes often need to measure their blood sugar levels throughout the day in order to understand their condition better and take necessary precautions. A sugar checking device mainly measures blood sugar levels and comes in different types. The most commonly found ones are a glucometer and a continuous glucose monitoring machine.




This website's content is provided only for educational reasons and is not meant to be a replacement for professional medical advice. Due to individual differences, the reader should contact their physician to decide whether the material is applicable to their case.