An In-depth Look at How Does Dexcom G7 Works

How Does Dexcom G7 Works

Table of Content

        • Introduction
        • The main components are Sensor, Transmitter, and Receiver.
        • What the sensor does: Measures Interstitial Fluid Glucose.
        • How the Transmitter Receives Relays the data
        • Personalized alerts, User Data, and Customized Alerts are shared through the app.


The first time that I had been diagnosed with Type 1 Diabetes more than a decade ago, coping with my condition was like an endless guessing game. The use of fingersticks multiple times throughout the day could only provide me with a few clues about what my glucose levels were and the direction they were taking. It was a highly frustrating method of living with such a critical medical disease.

It all changed when heard about CGM system for the  first time and learn how does it works. Being able to spot patterns and receive alerts without the need for finger pricks is life-changing. Even after having used various Dexcom different models for a while, there were some elements of how the technology functioned beneath my skin that I did not completely comprehend. This is why I decided to look into the technical complexities of the present Dexcom G7 system. This is a deeper review of its components and glucose monitoring procedure.

The main components are Sensor, Transmitter, and Receiver.

The core components in Dexcom G7 are the transmitter, sensor, and receiver. The tiny sensor, which is flexible, is made from hydrogel and includes an element for sensing made up of an enzyme membrane as well as electrodes. The element triggers a reaction between oxygen and glucose within the interstitial fluid beneath the skin’s surface to generate an electrical charge directly proportional to the concentration of glucose.

The sensor is then inserted inside the body, generally on the stomach or upper arms, with an applicator tool that is auto-inserted. The sensor remains there for a maximum of 10 days, after which a new sensor must be put in. The small portable transmitter is attached directly to the sensor following its insertion. It records the glucose level information by radio frequency to the sensor every five minutes.

This real-time information is transferred wirelessly, using Bluetooth to the receiver, which nowadays is typically a compatible phone or smartwatch that is loaded using the Dexcom G6 application. Some still have an individual receiver device, too. The app/receiver shows glucose readings as well as trends and warns users of changes.

What the sensor does: Measures Interstitial Fluid Glucose.

One question I used to ask was, how precisely can an instrument placed under the skin actually accurately reflect your blood sugar level? The interstitial fluid floating over our cells, just below the skin’s surface, matches our blood’s chemistry. Some key details:

  • Glucose quickly moves through blood vessels as well as interstitial fluids through capillary walls. The levels of this fluid are similar to those in blood.
  • The filament of the sensor is porous, which allows glucose molecules to move freely across its membrane from the interstitial fluid in our bodies to the enzyme or electrode sensor on the filament.
  • The enzyme specifically for glucose within this membrane reacts with glucose and produces an electrical current that is directly proportional to the glucose concentration. This is the current that sensors transmit to the transmitter.
  • When the test is repeated every 5 minutes, a moving average of the readings can reveal trends in glucose levels over time very precisely as compared to fingerstick test results.

While there is no direct measurement of blood levels, the Dexcom sensor’s measurements of interstitial fluid provide a highly accurate and clinically reliable view of the levels of glucose in blood beneath the skin.

How the Transmitter Receives Relays the data

The sensor filament creates an electrical current that corresponds to the levels of interstitial fluid glucose. The data signal is transmitted over a shorter distance toward the transmitter, which is then bonded to its top. These are the main features of the transmitter:

  • It has a receiver component that is tuned to the radio frequency of the sensor to detect signals from the reading of glucose.
  • Microchips that are small and powerful will process and calibrate raw signal reading, sifting out all interference with exclusive Dexcom algorithms.
  • The glucose value that is calibrated is assigned the proper time stamp, after which it is packaged with additional data, such as trend arrows, and the length of time since the sensor has been in place.
  • The information packet is sent to the app or receiver wirelessly using a Bluetooth signal at intervals of 5 minutes without the need for line-of-sight. The signal is able to travel as far as 30 feet.
  • In the event that someone is located further from their location or their phone is not in use, the data is restored once the connection is restored to ensure that the graph is up-to-date.

In summary, the transmitter is the crucial relay station between the sensor that is embedded within your body and the device that displays the data on the screen to users. Its functions include taking in, calibrating, and timing the glucose information read from the device.

Personalized alerts, User Data, and Customized Alerts are shared through the app.

One of the most significant aspects of Dexcom is that the Dexcom app and the user interface on watches and phones is the way that it permit the sharing and alert choices to become. Some of the personalization options I’ve found the most useful are:

  • Set alarms for upper or lower limits that vibrate or sound if the glucose levels are higher than specified targets, such as 70, 80, 120, 180, or 70 mg/dL, as required. They have certainly prevented the occurrence of poor hypos and hypers.
  • Arrows representing a rate of change indicate whether levels are moving upwards or downwards at a “fast” and “slow” rate. They are useful in predicting changes.
  • “Urgent Low Soon” and “Urgent High Soon” alerts are activated when changes in rates indicate that the levels are in danger of being close to levels.
  • The share feature allows trusted persons like parents, spouses, or doctors to have access only to my health trends, so they can tell that I’m safe far away.
  • The nighttime “Do not disturb” mode that shuts down alarms while you sleep but records all data until the morning when trends can be reviewed.


The ability to customize the Dexcom application to only the most important alerts at various times of the day or based on the events makes the system user-friendly. Sharing data from any location can help others in the event that levels are off. It’s an essential instrument for managing diabetes.

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Frequently Asked Questions

How does the Dexcom G7 compare to the previous G6 model?

The Dexcom G7 has several improvements over the G6. It is smaller in size and can transmit glucose readings every 5 minutes, compared to every 5-10 minutes in the G6. It also has a 10-day wear compared to the G6’s 7-10 days. The sensor insertion is now fully automated instead of manual as well. Overall accuracy is also improved in the G7.

How long does the transmitter battery last?

The Dexcom G7 transmitter uses a rechargeable battery that can last up to 10 days on a single charge. This allows it to seamlessly transmit glucose readings to the receiver/app for the full duration that the sensor is inserted. The transmitter battery can be easily recharged using the included charger.

How do I calibrate the Dexcom G7?

The Dexcom G7 uses an auto-calibration system and does not require any finger pricks for calibration. However, in certain situations such as when first applying the sensor, the system may ask users to obtain one or two finger prick readings to help fine-tune the calibration during the first 24 hours of sensor wear. After that initial period, no further calibration is needed.

Can I shower or swim with the Dexcom G7?

Yes, the Dexcom G7 is water-resistant and can withstand brief exposures to water such as showering, bathing or swimming. However, it should be avoided to fully submerge the transmitter in water. The sensor insertion area also needs to be covered with waterproof tape if undergone any water activities like swimming.

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