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Dexcom ONE Sensor - Single

Dexcom ONE Sensor - Single

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  • ✔️ Provides real-time glucose readings every 5 minutes automatically
  • ✔️ Worn continuously for up to 10 days per single sensor
  • ✔️ Suitable for adults and children aged 2 years and over
  • ✔️ Water-resistant to 2.4 metres — safe for showering and swimming
  • ✔️ No fingerprick calibration required throughout wear period

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What Is the Dexcom ONE Sensor and How Does It Help You Monitor Glucose?

 

Managing diabetes day to day can feel relentless. Fingerprick tests, logbooks, trying to spot patterns in numbers that seem to shift without warning — it takes real effort. The Dexcom ONE sensor is a single-use continuous glucose monitoring (CGM) device designed to take some of that burden away. Rather than relying on periodic fingerprick readings, it gives you a glucose reading every five minutes, automatically, for up to 10 days. That is up to 288 readings per day, all without a single prick. If you are looking to take a more informed approach to your diabetes management, you can explore our full range of products in our diabetes monitoring collection.

The sensor is worn discreetly on the back of the upper arm or abdomen and pairs with a compatible display device or smartphone app. It is suitable for adults and children aged 2 years and over with type 1 or type 2 diabetes. At £32.99 for a single sensor, it offers a practical entry point into CGM technology without committing to a multi-pack upfront.

 

How Does the Dexcom ONE Sensor Work in the Body?

 

The sensor uses a tiny, flexible filament — a biosensor — that sits just beneath the surface of the skin in the interstitial fluid. This fluid surrounds your body's cells and closely mirrors blood glucose levels, typically with a short lag of around 5–10 minutes. Here is how the process works:

  • A small applicator inserts the biosensor filament painlessly into the subcutaneous tissue.
  • The electrochemical biosensor reacts with glucose in the interstitial fluid using glucose oxidase chemistry.
  • An electrical signal is generated proportional to the glucose concentration present.
  • A transmitter attached to the sensor sends this data wirelessly to a compatible receiver or smartphone app every 5 minutes.
  • Trend arrows on the display show whether glucose is rising, falling, or stable — helping you make timely decisions about food, activity, or insulin.

Calibration is not required with the Dexcom ONE, which simplifies the experience considerably compared with older CGM systems.

 

Who Should Use the Dexcom ONE Sensor?

 

The Dexcom ONE sensor is suitable for a wide range of people living with diabetes. It is particularly useful if you find fingerprick testing disruptive, if you experience hypoglycaemia unawareness, or if you simply want a clearer picture of how your glucose responds to meals, exercise, and stress. That said, it is not a replacement for all clinical glucose testing — your diabetes care team can advise on when fingerprick confirmation is still needed.

It may be especially appropriate for:

  • Adults with type 1 or type 2 diabetes who self-manage their condition.
  • Children aged 2 years and over, under parental or carer supervision.
  • People who experience frequent hypoglycaemic episodes or hypoglycaemia unawareness.
  • Those who want to understand glucose trends around meals, exercise, or medication changes.

 

How Does the Dexcom ONE Sensor Compare to Other CGM Options?

 

Feature Dexcom ONE Sensor FreeStyle Libre 2 Sensor
Wear duration Up to 10 days Up to 14 days
Reading frequency Every 5 minutes (automatic) On scan (every 1 minute when scanned)
Real-time alerts Yes — high and low glucose alerts Yes (Libre 2 only)
Calibration required No No
Water resistance Up to 2.4 m for 24 hours Up to 1 m for 30 minutes

 

How Should You Store the Dexcom ONE Sensor and Is It Clinically Suitable for You?

 

The Dexcom ONE sensor should be stored below 30°C, away from direct sunlight and moisture. Do not freeze the sensor or expose it to extreme heat, as this can affect the accuracy of the biosensor filament. Once applied to the skin, the sensor is designed to function reliably for the full 10-day wear period under normal conditions, including showering and light swimming. You can also browse our electrical health and diagnostic range for other monitoring devices that complement your diabetes care routine.

Before starting CGM, it is worth discussing your individual circumstances with your GP or diabetes nurse. Certain medications — particularly high-dose paracetamol — may interfere with sensor accuracy. People with implanted electronic devices such as pacemakers should also seek medical advice before use.

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

Dexcom ONE Sensor - Single specifications
Treatment category Continuous glucose monitoring (CGM)
Mechanism of action Electrochemical glucose oxidase biosensor measuring interstitial glucose
Effective Up to 10 days per sensor
Suitable for Adults and children aged 2 years and over with diabetes
Active ingredient Glucose oxidase electrochemical biosensor (non-pharmacological device)
Pack sizes Single sensor
UK classification Medical device (CE/UKCA marked)
Preparation Single-use wearable sensor with integrated transmitter
Route of administration Subcutaneous (applied to skin surface via applicator)

Specifications of Dexcom ONE Sensor - Single

 

What Is the Dexcom ONE Sensor and What Is It Used For?

 

The Dexcom ONE sensor is a continuous glucose monitoring (CGM) device used by people with diabetes to track their glucose levels in real time throughout the day and night. Unlike traditional blood glucose meters that give you a single snapshot reading, the Dexcom ONE provides a continuous stream of glucose data — one reading every five minutes — for up to 10 days per sensor. This helps you and your healthcare team understand how your glucose responds to food, physical activity, stress, illness, and medication.

It is used primarily by people with type 1 or type 2 diabetes who need to monitor their glucose levels regularly. The NHS recognises CGM as a clinically valuable tool for improving glycaemic control and reducing the risk of hypoglycaemia. The sensor does not deliver any medication — it is purely a monitoring device.

 

What Do You Need to Know Before Using the Dexcom ONE Sensor?

 

Before applying the sensor, there are some important contraindications and precautions to be aware of. Please read these carefully.

Do not use the Dexcom ONE sensor if:

  • You are allergic to any of the materials in the sensor or adhesive patch.
  • You have a known sensitivity to medical-grade adhesives.
  • You are undergoing MRI scanning, CT scanning, or diathermy — remove the sensor before these procedures.
  • You are under 2 years of age.

Use with caution and seek medical advice if:

  • You have an implanted electronic device such as a pacemaker or neurostimulator.
  • You are pregnant — CGM can be used in pregnancy but discuss with your obstetric team first.
  • You have significant peripheral oedema or poor skin integrity at the intended application site.
  • You are critically ill or in hospital — sensor accuracy may be reduced in these settings.

Known interactions that may affect sensor accuracy:

  • High-dose paracetamol (acetaminophen) — doses above 1 g may cause falsely elevated glucose readings.
  • Hydroxyurea — may affect sensor performance.
  • Mannitol infusions — may interfere with interstitial glucose measurement.

 

How Should You Use the Dexcom ONE Sensor Step by Step?

 

Applying the sensor correctly is important for accurate readings and comfortable wear. Follow these steps carefully:

  1. Wash your hands thoroughly with soap and water and dry them completely.
  2. Choose your application site — the back of the upper arm or abdomen (avoid the waistband area). Rotate sites with each new sensor.
  3. Clean the skin with an alcohol wipe and allow it to dry fully for at least 30 seconds.
  4. Remove the sensor from its packaging, taking care not to touch the adhesive or the sensor tip.
  5. Press the applicator firmly against the skin and press the button to insert the sensor filament.
  6. Remove the applicator, leaving the sensor and transmitter in place on the skin.
  7. Open the Dexcom ONE app on your compatible smartphone or turn on your receiver device.
  8. Follow the on-screen pairing instructions to connect the sensor to your display device.
  9. Allow a 2-hour warm-up period before the sensor begins providing readings.
  10. Check the trend arrows regularly and respond to any high or low glucose alerts as advised by your diabetes care team.
User Group Application Site Supervision Required Wear Duration
Adults (18+) Upper arm or abdomen No Up to 10 days
Children (2–17 years) Upper arm (recommended) Yes — parent or carer Up to 10 days

 

What Are the Possible Side Effects of the Dexcom ONE Sensor?

 

As with any wearable medical device, some people experience reactions at the application site. Most are mild and resolve once the sensor is removed. If you experience a severe allergic reaction — including widespread rash, swelling, or difficulty breathing — remove the sensor immediately and seek urgent medical attention.

Common side effects:

  • Redness or erythema at the sensor site
  • Mild itching or pruritus under the adhesive patch
  • Minor bruising or tenderness at the insertion point
  • Skin irritation from the adhesive

Less common side effects:

  • Allergic contact dermatitis — a more pronounced skin reaction to the adhesive materials
  • Sensor inaccuracy leading to unexpected high or low glucose alerts
  • Sensor detachment before the 10-day wear period ends
  • Discomfort or pain at the insertion site, particularly in leaner individuals

If you notice persistent skin reactions, speak to your pharmacist or GP. Barrier films or hypoallergenic adhesive patches can sometimes help if you have sensitive skin. You might also find it useful to browse our skin care collection for products that support skin health around wearable devices.

 

How Should You Store the Dexcom ONE Sensor?

 

Correct storage protects the integrity of the biosensor and ensures accurate readings throughout the wear period.

  • Store unopened sensors below 30°C — do not refrigerate or freeze.
  • Keep away from direct sunlight and sources of heat.
  • Store in a dry environment — avoid bathrooms or areas with high humidity.
  • Do not use a sensor past its expiry date, printed on the individual packaging.
  • Once applied to the skin, the sensor can be exposed to water (showering, swimming) up to 2.4 metres depth for up to 24 hours.
  • Keep out of reach of children when not in use.
  • Dispose of used sensors in accordance with your local clinical waste or sharps disposal guidelines — contact your GP surgery or pharmacy for a sharps bin if needed.

For people managing multiple aspects of their health alongside diabetes, our vitamins and supplements collection includes products that may support general wellbeing as part of a broader health routine.

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Frequently Asked Questions

Where can I buy the Dexcom ONE sensor online in the UK?

You can buy the Dexcom ONE sensor single online from Cured Pharmacy, a GPhC-registered UK online pharmacy, at £32.99 per sensor. No prescription is required, making it straightforward to order and have it delivered to your door. Browse our full diabetes monitoring collection for related products.

How does the Dexcom ONE sensor work in the body?

The Dexcom ONE sensor uses a tiny electrochemical biosensor filament inserted just beneath the skin to measure glucose in the interstitial fluid — the fluid that surrounds your body's cells. It generates an electrical signal proportional to the glucose concentration, which is transmitted wirelessly to a compatible app or receiver every 5 minutes. This gives you a continuous, real-time picture of your glucose levels and trends throughout the day and night.

How long does the Dexcom ONE sensor last before I need to replace it?

Each Dexcom ONE sensor is designed to last up to 10 days of continuous wear before it automatically expires and needs replacing. After 10 days, the sensor will stop transmitting readings and you will need to apply a fresh sensor to continue monitoring. Rotating your application site with each new sensor helps protect skin health.

Do I need a prescription to buy the Dexcom ONE sensor in the UK?

No, the Dexcom ONE sensor is available without a prescription in the UK as it is classified as a medical device rather than a prescription medicine. However, it is strongly recommended that you discuss continuous glucose monitoring with your GP or diabetes care team before starting, particularly if you are adjusting your insulin regimen based on CGM readings. Your team can also advise on whether you may be eligible for NHS-funded CGM.

Can I shower or swim while wearing the Dexcom ONE sensor?

Yes, the Dexcom ONE sensor is water-resistant and suitable for showering, bathing, and swimming. It is rated to withstand immersion in up to 2.4 metres of water for up to 24 hours, so everyday water exposure is not a concern. Avoid prolonged submersion beyond these limits, such as deep-water diving, as this may compromise the sensor's integrity.

What are the side effects of the Dexcom ONE sensor?

The most commonly reported side effects are mild skin reactions at the application site, including redness, itching, and minor bruising — these typically resolve once the sensor is removed after 10 days. Less commonly, some people experience allergic contact dermatitis from the adhesive patch. If you develop a severe skin reaction, widespread rash, or any signs of anaphylaxis, remove the sensor immediately and seek urgent medical attention.

Is the Dexcom ONE sensor suitable for children?

Yes, the Dexcom ONE sensor is indicated for use in adults and children aged 2 years and over who have diabetes. Children under 18 should use the sensor under the supervision of a parent or responsible adult, and the sensor should be applied and managed in line with guidance from the child's diabetes care team. The upper arm is the recommended application site for paediatric users.

How does the Dexcom ONE sensor compare to the FreeStyle Libre 2?

The Dexcom ONE provides automatic glucose readings every 5 minutes without needing to scan, whereas the FreeStyle Libre 2 requires you to scan the sensor to obtain a reading (though it does send optional real-time alerts). The Dexcom ONE wears for up to 10 days compared to the Libre 2's 14-day wear period. Both are calibration-free and suitable for adults and children, but the right choice depends on your lifestyle and the features your diabetes team recommends.

How do I apply the Dexcom ONE sensor correctly?

Clean your chosen site — the back of the upper arm or abdomen — with an alcohol wipe and allow it to dry fully. Press the applicator firmly against the skin and activate it to insert the sensor filament, then remove the applicator and pair the sensor with your compatible smartphone app or receiver. Allow a 2-hour warm-up period before the sensor begins providing glucose readings.

What happens if my Dexcom ONE sensor falls off before 10 days?

If the sensor detaches from the skin before the 10-day wear period ends, it cannot be reapplied — you will need to use a new sensor. To help prevent early detachment, ensure the skin is clean, dry, and free from lotions or oils before application. Some people find that using an additional over-patch adhesive helps the sensor stay in place during exercise or in hot weather.

Can paracetamol affect the accuracy of the Dexcom ONE sensor?

Yes, high doses of paracetamol — typically above 1 gram — can cause the Dexcom ONE sensor to display falsely elevated glucose readings. Standard therapeutic doses taken occasionally are less likely to cause significant interference, but if you regularly take paracetamol for pain relief, discuss this with your pharmacist or diabetes team. You can explore our pain relief collection for alternative options if needed.

Who is eligible for a free Dexcom ONE sensor on the NHS?

NHS eligibility for CGM devices, including the Dexcom ONE, is determined by NICE guidelines and local integrated care board (ICB) policies. Generally, people with type 1 diabetes who meet specific clinical criteria — such as recurrent hypoglycaemia or impaired hypoglycaemia awareness — may be eligible for NHS-funded CGM. Speak to your GP or diabetes specialist nurse to find out whether you qualify in your area.

How long can I use continuous glucose monitoring with the Dexcom ONE?

There is no fixed maximum duration for using CGM — many people with diabetes use it continuously as an ongoing part of their diabetes management. Each individual sensor lasts 10 days, after which you simply apply a new one. Long-term CGM use has been associated with improved glycaemic control and reduced hypoglycaemia frequency in clinical studies, and your diabetes team can advise on whether sustained use is appropriate for you.

What are the latest findings on continuous glucose monitoring for type 2 diabetes?

Research into CGM for type 2 diabetes has grown considerably in recent years. Studies published in peer-reviewed journals have shown that real-time CGM can help people with insulin-treated type 2 diabetes reduce HbA1c levels and time spent in hypoglycaemia. NICE updated its guidance in 2022 to extend CGM recommendations to a broader group of people with type 2 diabetes on insulin, reflecting this growing evidence base.

What should I do if I get a skin reaction from the Dexcom ONE sensor adhesive?

Mild redness or itching under the adhesive patch is relatively common and usually settles within a day or two of removing the sensor. If you have sensitive skin, rotating your application site with every new sensor and allowing the previous site to fully recover can help. For persistent or worsening reactions, speak to your GP or pharmacist — they may recommend a barrier film or hypoallergenic over-patch to reduce direct adhesive contact with the skin.

How Should You Use the Dexcom ONE Sensor?

Applying the Dexcom ONE sensor correctly makes a real difference to both comfort and accuracy. Before you start, make sure your hands are clean and the skin at your chosen site is free from lotions, oils, and moisture — these can all affect how well the adhesive bonds and how accurately the sensor reads.

What Is the Correct Dose of the Dexcom ONE Sensor?

The Dexcom ONE is a medical device, not a medication, so there is no pharmacological dose. However, the correct "dose" in practical terms is one sensor applied at a time, worn continuously for up to 10 days. Applying more than one sensor simultaneously is not recommended and will not improve accuracy.

When Is the Best Time to Use the Dexcom ONE Sensor?

There is no single "best" time of day to apply a new sensor, but many people find it helpful to apply a fresh sensor in the evening so that the 2-hour warm-up period passes overnight. This means you wake up with a fully active sensor ready to track your morning glucose levels — often one of the most informative periods of the day for people with diabetes. Try to avoid applying the sensor immediately before a meal or exercise session, as the warm-up period means you will not have readings available during that time.

How Long Can You Use the Dexcom ONE Sensor For?

Each individual sensor lasts up to 10 days, after which it expires automatically and must be replaced with a new one. There is no clinical limit on how long you can continue using CGM overall — many people use it as a permanent part of their diabetes management for months or years. Your diabetes care team can advise on whether ongoing CGM is appropriate for your individual situation and whether you may be eligible for NHS-funded sensors.

Do not exceed the recommended dose. If in doubt, speak to your pharmacist.

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What Are the Most Common Side Effects of the Dexcom ONE Sensor?

Because the Dexcom ONE sensor is a wearable device rather than an ingested medicine, its side effects are primarily localised to the skin at the application site. Most people tolerate the sensor well, but some degree of skin reaction is not unusual — particularly if you have sensitive skin or are new to wearing CGM devices.

  • Redness (erythema) at or around the sensor site
  • Mild itching or pruritus under the adhesive patch
  • Minor bruising or tenderness at the point of sensor insertion
  • Slight swelling or warmth at the application site

What Are the Less Common Side Effects of the Dexcom ONE Sensor?

Less frequently, some users experience more pronounced reactions that may require attention. These are not dangerous in most cases, but they can be uncomfortable and may affect your ability to continue wearing the sensor at the same site.

  • Allergic contact dermatitis — a more significant inflammatory skin reaction to the adhesive materials
  • Skin maceration (softening and breakdown) if the adhesive traps moisture against the skin
  • Sensor detachment before the 10-day wear period ends, particularly in hot or humid conditions
  • Discomfort or pain at the insertion site, more likely in people with lower body fat at the application area
  • Inaccurate glucose readings — this can occur if the sensor is applied incorrectly, if the site is compressed (e.g. sleeping on the sensor), or if interfering substances such as high-dose paracetamol are present

What Are the Serious Side Effects of the Dexcom ONE Sensor?

Serious adverse reactions to the Dexcom ONE sensor are rare but possible. The most significant concern is a severe allergic reaction (anaphylaxis) to the sensor materials or adhesive. Signs of a serious reaction include widespread rash or hives, facial swelling, difficulty breathing, or a sudden drop in blood pressure. If you experience any of these symptoms, remove the sensor immediately and call 999 or go to your nearest A&E department without delay. Infection at the insertion site is also possible, though uncommon — signs include increasing pain, warmth, pus, or fever.

What Should You Do If You Experience Side Effects from the Dexcom ONE Sensor?

For mild skin reactions, removing the sensor and allowing the site to recover is usually sufficient. Rotating your application site with every new sensor — and ensuring the skin is fully healed before reusing a site — significantly reduces the risk of cumulative irritation. If you have a known adhesive sensitivity, speak to your pharmacist or diabetes nurse before starting; they may recommend a barrier film or hypoallergenic over-patch. Keep a note of any reactions and share this information with your diabetes care team at your next appointment.

Can the Dexcom ONE Sensor Interact With Other Medicines or Devices?

The Dexcom ONE sensor is not a medicine and does not interact with other drugs in the traditional pharmacological sense. However, certain substances can affect the accuracy of the glucose readings it produces. High-dose paracetamol (above 1 g) is the most clinically significant, as it can cause falsely elevated readings. Hydroxyurea and mannitol infusions may also interfere with sensor performance. Additionally, people with implanted electronic devices such as pacemakers, neurostimulators, or cochlear implants should seek medical advice before using the sensor, as electromagnetic interference is theoretically possible. MRI, CT, and diathermy procedures require the sensor to be removed beforehand.

If you are concerned about any side effects, contact your pharmacist or GP immediately.

Patient Information Leaflet

Important - Before taking any medication, it is always important to read the Patient Information Leaflet (PIL)

Written and reviewed by our qualified team

GPhC Number: 2233073
Tarun Kumar

Reviewed by:

Tarun Kumar

Superintendent/ Clinical Lead

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Content last updated: 31 Mar 2025

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