Dexcom OneTransmitter

What Is the Dexcom One Transmitter?

If you're living with diabetes and want to move away from constant finger-prick testing, the Dexcom One transmitter is a key part of making that possible. It's the small, reusable device that clips onto your Dexcom One sensor and wirelessly sends your glucose readings to your smartphone or compatible display device — every five minutes, around the clock. Managing blood glucose is one of the most important aspects of diabetes care, and continuous glucose monitoring (CGM) technology has genuinely changed how people do that day to day. You can explore a wider range of CGM products and accessories in our diabetes monitoring collection.

The transmitter itself is compact and discreet. It sits flat against your skin, attached to the sensor pod, and most people barely notice it's there. At £34.99, it represents a straightforward replacement option when your existing transmitter reaches the end of its battery life — typically around three months of continuous use.

How Does the Dexcom One Transmitter Work?

The transmitter works in close partnership with the Dexcom One sensor, which sits just beneath the skin's surface and measures interstitial glucose levels. Here's how the process flows:

• The sensor measures glucose in the fluid between your cells (interstitial fluid) continuously.
• The transmitter receives this raw glucose data from the sensor electrochemically.
• It converts and transmits the data via Bluetooth to the Dexcom One app on your smartphone or a dedicated receiver.
• Readings appear on your screen every five minutes, with trend arrows showing whether your glucose is rising, falling, or stable.
• Customisable alerts notify you if your glucose goes above or below your set thresholds.

The transmitter doesn't require any manual activation once it's clipped into the sensor. It pairs automatically with your device and begins transmitting as soon as the sensor warm-up period is complete — typically around two hours for the Dexcom One system.

Who Should Use the Dexcom One Transmitter?

The Dexcom One system — and therefore this replacement transmitter — is suitable for a broad range of people managing diabetes. It's particularly useful if you find finger-prick testing disruptive, painful, or difficult to maintain consistently throughout the day.

• Adults with type 1 diabetes who require frequent glucose monitoring.
• Adults with type 2 diabetes using insulin therapy.
• People who experience hypoglycaemia unawareness and need overnight alerts.
• Those who want to share glucose data with a carer or family member via the Dexcom Follow app.

It is not currently licensed for use in children under two years of age. If you are pregnant or planning to become pregnant, speak to your diabetes care team before starting or continuing CGM use, as monitoring targets may differ.

How Does the Dexcom One Transmitter Compare to Alternatives?

Is the Dexcom One Transmitter Suitable for Everyday Wear?

Absolutely. The Dexcom One transmitter is designed for continuous, everyday wear. It's water-resistant to a depth of 2.4 metres for up to 24 hours, so showering, swimming, and exercise are all fine. The low-profile design means it sits comfortably under clothing without snagging or causing discomfort for most users. If you do experience any skin irritation around the sensor site — which can occasionally happen with adhesive-based wearables — speak to your diabetes care team about barrier films or alternative placement sites. You might also find it helpful to browse our electrical health and diagnostic range for complementary monitoring tools.

This product is a medical device. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

What Is the Dexcom One Transmitter and What Is It Used For?

The Dexcom One transmitter is a reusable medical device component that forms part of the Dexcom One continuous glucose monitoring (CGM) system. It is used by people with diabetes to receive real-time glucose readings without the need for routine finger-prick blood tests. The transmitter clips onto the Dexcom One sensor — which is worn on the back of the upper arm or abdomen — and wirelessly sends glucose data to a compatible smartphone running the Dexcom One app, or to a dedicated receiver.

CGM systems like the Dexcom One are recommended by NHS England for people with type 1 diabetes and for some people with type 2 diabetes who use insulin. The transmitter itself needs replacing approximately every three months when its battery is depleted, making this a routine purchase for existing Dexcom One users.

What Do You Need to Know Before Using the Dexcom One Transmitter?

Before attaching a new transmitter, there are some important considerations to be aware of. This device is not suitable for everyone, and certain conditions or medications may affect its accuracy or suitability.

Do not use this transmitter if:

• You are allergic to any of the materials used in the transmitter or sensor adhesive.
• You are using a non-compatible Dexcom sensor (the transmitter is only compatible with Dexcom One sensors).
• The transmitter is damaged, cracked, or has been submerged beyond its rated depth or duration.
• You are undergoing MRI, CT scanning, or diathermy — remove the entire sensor and transmitter system before these procedures.

Warnings and precautions:

• Do not use CGM readings as the sole basis for insulin dosing decisions without confirming with a finger-prick test if symptoms do not match the reading.
• Inform your diabetes care team if you notice consistently inaccurate readings.
• Keep the transmitter away from strong electromagnetic fields, including airport security scanners where possible.

Medicines that may affect sensor accuracy:

• High-dose paracetamol (acetaminophen) may cause falsely elevated glucose readings.
• Hydroxyurea has been reported to affect CGM sensor accuracy in some systems — discuss with your care team.

How Should You Use the Dexcom One Transmitter?

Setting up your new transmitter is straightforward, but following the steps in order matters. Rushing the process can lead to pairing errors or inaccurate readings during the warm-up phase.

1. Wash and dry your hands thoroughly before handling the transmitter or sensor.
2. Insert the Dexcom One sensor into the applicator and apply it to clean, dry skin on the back of your upper arm or abdomen.
3. Slide the transmitter into the sensor pod from the narrow end until you hear or feel a click.
4. Open the Dexcom One app on your compatible smartphone and select "Start Sensor."
5. Enter the transmitter serial number when prompted (found on the transmitter packaging).
6. Allow the two-hour warm-up period to complete before relying on readings.
7. Confirm your first reading with a finger-prick blood glucose test if required by your care team.

What Are the Possible Side Effects of the Dexcom One Transmitter?

As a wearable medical device rather than a medicine, the Dexcom One transmitter does not cause systemic side effects. However, wearing any adhesive device on the skin for extended periods can cause localised reactions in some people. If you experience persistent discomfort, it's worth speaking to your diabetes care team. You can also explore our skin care collection for products that may help manage minor irritation around the sensor site.

Common side effects (at the sensor/transmitter site):

• Mild redness or erythema around the adhesive patch.
• Itching beneath or around the sensor.
• Minor bruising at the insertion site.
• Temporary skin indentation after sensor removal.

Less common side effects:

• Allergic contact dermatitis to the adhesive or sensor materials.
• Skin breakdown or maceration with prolonged wear in humid conditions.
• Bleeding at the insertion site (usually minor and self-limiting).

How Should You Store the Dexcom One Transmitter?

Proper storage helps maintain the transmitter's battery integrity and electronic components. Follow these guidelines:

• Store below 30°C and away from direct sunlight.
• Keep in a dry environment — avoid bathrooms or areas with high humidity when not in use.
• Do not freeze the transmitter or expose it to temperatures below 10°C for extended periods.
• Keep out of reach of children.
• Do not store near strong magnets or electronic devices that emit strong electromagnetic fields.
• Once attached to a sensor, the transmitter should remain in place for the duration of the sensor session.

For broader diabetes management support, including blood glucose meters and testing supplies, visit our diabetes monitoring collection at Cured Pharmacy.