CGMs have enabled people without type 1 and type 2 diabetes to be exposed to the world of blood glucose levels and time in range. But is that a good thing?

Our in-depth article explores the advantages and disadvantages of CGMs for people with and without diabetes and how this technology is being integrated into wider health and lifestyle management.

What are CGMs?

CGMs are devices that continuously track blood glucose levels through the body’s interstitial fluid.

This provides a dynamic, real-time view of blood sugar patterns throughout the day and night.

CGMs typically comprise a small sensor inserted under the skin and a transmitter that sends the data to a monitor or smartphone. Some CGMS have displays that show blood glucose information in real time.

• FreeStyle Libre 2: update enables use as a continuous glucose monitor
• CGM Sensors: How They Work, Sensor Placement and Care

Advantages of CGMs

In the evolving landscape of diabetes technology, CGMs have transformed how people with type 1 diabetes in particular manage their blood glucose levels.

Improved blood glucose control

CGMs provide real-time feedback and trends which enable individuals to manage their blood glucose levels more effectively.

Peeople are able to see the impact certain foods, exercise, stress and medications can have on their blood sugar levels.

CGMs also allow people to see how long their blood glucose levels are in range.

This can lead to significant improvements in blood glucose control and thereby reducing the risk of diabetes-related complications.

Hypo and hyperglycemia prevention

By alerting users to sudden drops or spikes in glucose levels, CGMs can help prevent severe hypoglycemia (low blood sugar) and persistent hyperglycemia (high blood sugar) which are common challenges for people with diabetes.

Alerts can be set to notify people on when they are getting close to going hypo or hyper.

• Hypoglycemia (low blood glucose levels)
• What is a Hypo: Hypo Causes, Symptoms and Treatment

Reduced need for fingerstick testing

CGMs can decrease or sometimes eliminate the need for traditional blood glucose testing via finger pricks, offering a less invasive and more convenient monitoring method.

Closed-loop insulin delivery systems

Also known as the “artificial pancreas” closed-loop insulin delivery systems continuously monitor blood glucose levels and automatically adjust insulin delivery in real time.

This significantly reduces the burden of constant monitoring and manual insulin adjustment, improving glycemic control and reducing the risk of both hypoglycemia and hyperglycemia.

• Artificial Pancreas: Hybrid closed-loop system gets NHS green light
• Artificial pancreas improves blood sugar control in young children with type 1 diabetes

Are there advantages for people without diabetes?

It has become commonplace to hear of people without diabetes using CGMs.

Athletes and sports enthusiasts are increasingly turning to CGMs as a tool to optimise performance and recovery.

For athletes, maintaining optimal blood glucose levels is crucial for sustained energy, endurance, and performance.

CGMs are used as a window into how their bodies respond to various types of training, the impact of stress, and the effect of their diet on glucose levels.

Real-time data allows athletes to fine-tune their nutrition and training regimes, ensuring that they are fueling their bodies appropriately before, during, and after exercise to maintain energy levels and accelerate recovery.

By avoiding the peaks and troughs of blood glucose levels, athletes can potentially reduce the risk of energy dips and improve their overall metabolic efficiency.

The adoption of CGMs by sports people highlights a broader trend of leveraging health technology not only for disease management but also for enhancing physical performance and wellbeing.

For people without diabetes, CGMs can provide fascinating insights into how their diet, exercise, and stress levels affect their blood sugar levels, enabling more informed lifestyle choices.

• What should my blood sugar levels be?
• Time in Range

For example, feeling tired after meals, a condition often referred to as postprandial somnolence or the “food coma” can sometimes be linked to fluctuations in blood glucose levels. High blood glucose following a meal can trigger this sensation of fatigue as the body works harder to manage and utilise the excess sugar.

CGMs can be used as a useful tool in this context by offering real-time insights into how specific foods and meal compositions impact glucose levels.

CGMs can also serve as a tool for preventive health and help to avoid the onset of type 2 diabetes and other metabolic conditions.

Disadvantages of CGMs

While CGMs are innovative devices that have transformed diabetes management, there are several disadvantages that have been noted.

Cost

CGMs can be expensive.

Skin irritation

Some users may experience skin irritation from the adhesive used to hold the CGM’s sensor in place.

Additionally, having a device attached to the body continuously can be uncomfortable for some.

Accuracy

While CGM technology has improved significantly, discrepancies can still occur, especially in the case of rapid glucose changes. Users must be prepared to verify readings with fingerstick tests if needed.

Reliance on software

A number of software issues have rendered CGMs useless for people with diabetes. These issues have highlighted reliance on software and Internet-enabled technologies.

• Omnipod 5 insulin system reports decimal point glitch
• FreeStyle LibreLink app update glitch sparks alarm among Apple users

Should people without diabetes use CGMs?

CGMs offer novel insights into blood glucose management and their use in people without diabetes comes with specific challenges and considerations.

Unnecessary anxiety

While data is always useful to make better decisions, when CGMs are used by people without diabetes it can cause unnecessary anxiety or an obsession with numbers.

Continuous access to glucose data can lead some individuals to fixate on minor fluctuations in their blood sugar levels.

In the context of an individual without diabetes, these may be within a normal range and not a cause for concern. Hyper-awareness can contribute to stress and anxiety, which ironically, can themselves impact glucose levels.

Misinterpretation

The wealth of data provided by CGMs can be both a blessing and a curse.

For those without a medical background or thorough understanding of metabolism, there is a significant risk of misinterpreting the data.

Physiological responses to food, exercise, and stress can cause variations in glucose levels that are normal but might be perceived as problematic.

Misinterpretation could lead to unnecessary dietary restrictions or lifestyle changes.

Overreliance on technology

CGMs can make it easy to become over-reliant on technology for health and lifestyle decisions.

The immediate feedback loop provided by CGMs might lead some people to trust the technology more than their own bodily signals, such as hunger, fullness, and fatigue.

Over-reliance on technology can detract from developing intuitive eating practices and listening to the body’s natural cues.

As with any health technology, it’s essential for individuals to consult healthcare professionals to determine if CGMs are a suitable option for their personal health and lifestyle needs.

What is Time in Range?

Time in Range is the percentage of time a person’s blood glucose levels are within a specified target range.

Typically, this would be between 4 mmol/L and 10 mmol/L, or whatever targets you have agreed with your healthcare team.

The goal with managing diabetes is to maximise the “time in range” and to minimise high and low sugar levels.

By doing this, blood glucose levels remain stable and this can reduce the risk of short-term and long-term health complications.

• Blood Sugar Level Ranges
• How To Test Your Blood Glucose
• How To Inject Insulin

How to calculate Time in Range?

To calculate Time in Range from your blood glucose readings manually, follow these steps:

1. Define your target blood glucose range
2. Collect your blood glucose readings – either from your CGM or blood glucose meter
3. Count how many readings fall within your defined target glucose range during the period you are analysing
4. Calculate the percentage of time in the target range using the formula, expressed as a percentage of the total monitoring time

Time in Range (%) = [Number of readings within target range / Total number of readings] * 100

For example, if you have 288 readings in a 24-hour period (assuming most CGM devices record a reading every 5 minutes), and 230 of these readings are within the target range, the calculation would be:

Time in Range (%) = [230 / 288] * 100 = 79%

Typical Time in Range targets are for people with diabetes, based on guidelines and clinical recommendations:

References: American Diabetes Association (ADA) Standards of Medical Care in Diabetes (2023); International Consensus on Time in Range (2019); Advanced Technologies & Treatments for Diabetes (ATTD) Consensus Report (2019).

Why Time in Range matters?

Time in Range gives a far more detailed understanding of blood glucose control compared to the traditional HbA1c test.

HbA1c tests give you an average glucose level over 90 days but fail to reveal daily blood glucose fluctuations, or the frequency of highs and lows.

Time in Range gives a comprehensive view of a person’s daily blood glucose control.

It shows how diet, physical activity, and medications influence blood sugar levels.

This detailed understanding is essential in preventing the rollercoaster-like effects of fluctuating blood glucose levels and help to reduce the risk of both hypoglycemia and hyperglycemia.

For people with diabetes, an HbA1c level of 48mmol/mol (6.5%) or below is considered ideal. This equates to having a time in range of 80%.  

The clinical importance of Time in Range

Research has shown that a higher Time in Range, that is, spending more time with your blood glucose levels between your target thresholds, is linked to a reduced risk of diabetes complications.

Time in Range is becoming a key endpoint in clinical trials evaluating new diabetes therapies, highlighting its importance as a predictor of treatment efficacy and patient outcomes.

Monitoring Time in Range

While monitoring Time in Range may seem cumbersome, it’s actually very simple.

Continuous glucose monitors (CGMs) and systems such as the Freestyle Libre 2 provide real-time blood glucose readings allowing you to track fluctuations throughout the day and night.

This continuous stream of data allows you and your healthcare team to assess your blood glucose control accurately.

Most CGMs come with apps that show your Time in Range.

• Buy a Freestyle Libre 2
• FreeStyle Libre 2: update enables use as a continuous glucose monitor
• How do CGM sensors work?

What’s more, the data that comes from your CGM can also help you to identify trends, such as times of day when blood sugar levels are most volatile, guiding more precise guidance on how to optimise blood glucose management.

Using Time in Range data

Time in Range data has several practical applications:

• It enables you to make more informed treatment decisions
• It enables your healthcare provider to design tailored interventions like medication dosages, dietary plans, and exercise regimens according to your unique biology
• Maintaining Time in Range can significantly reduce the risk of diabetes-related complications
• Time in Range empowers people with immediate feedback on their choices and develops a more engaged, proactive approach to health

Alongside HbA1c, Time in Range gives you an effective way of understanding your state of diabetes control.

How does a CGM sensor work?

Continuous glucose monitors measure the glucose in your interstitial fluid – a thin layer of fluid which surrounds the body’s cells and provides them with nutrients.

For people with diabetes, monitoring your glucose levels at all times can make all the difference when it comes to controlling your glucose levels and avoiding blood sugar spikes.

A CGM is typically placed on the back of your upper arm, where it is most safe from knocks as you go about your daily life.

If you’ve just received your first CGM and need help applying the sensor, or you’ve been having trouble making your sensor stay on, below is a step-by-step guide on sensor placement and adhesion.

Finding the right CGM sensor application site

Most sensors are placed on the back of the upper arm, where it’s less likely to brush against things such as doorways, although some sensors can also be applied to your abdomen, thigh, buttocks or back.

If you’re unsure where to put your sensor, check the information booklet that came with your device, or consult your doctor.

You must avoid using body lotions or creams on the area as this can interfere with readings and impair the sensor’s adhesion.

Select a smooth area of skin free from birthmarks, stretch marks, scars or lumps at least one inch away from where you would usually inject your insulin.

Preparing your skin

When cleaning the area where you plan to place your sensor, ensure you use a non-moisturising fragrance-free soap. Instead, a moisture-free alcohol wipe that doesn’t contain ingredients such as glycerol can be used to clean the skin.

Try to let your skin air dry before applying the sensor.

Depending on your skin type, you may have to spend a little extra time ensuring the skin is ready for the sensor to be applied. While this can be inconvenient, it can significantly improve the sensor’s adhesion, meaning it will last for longer.

Extra steps for your skin type

If you have oily skin, lotions, soaps, shampoos and hair conditioners can leave an oily residue on your skin, compromising how well the sensor sticks to your skin.

After following the steps above to ensure a clean sensor site, use an alcohol wipe to remove an excess oily residue from your skin.

For hairy skin, simply shaving the area until it is free from excess hair will help the sensor stay in place.

Applying your CGM sensor

Most sensors are applied to the skin the same way. However, there might be some differences between brands.

The steps below are a broader guide to sensor application – always consult the information booklet which came with your device for the exact instructions.

• Remove the lid from your new sensor and push it into the sensor applicator. Most sensors will have a guide (usually a mark or line) that indicates the sensor and applicator are aligned correctly.
• With the skin area prepared, place the loaded applicator over the application site. Push firmly until the sensor is in place. Afterwards, remove the applicator by carefully pulling it away.
• With the sensor attached to your skin, ensure it is secure by gently running your finger across its edge.

Caring for your sensor

It’s almost inevitable that one of your sensors will accidentally fall off at some point, whether that’s due to it catching on tight clothing or getting knocked on furniture. However, you can take some extra steps to try and keep your sensor in place.

Be wary of furniture – particularly the edges, doorways and even car seatbelts.

Loose clothing will allow your sensor to breathe and make it harder to get caught on tight clothes.

Avoid touching your sensor unnecessarily, and be careful around children curious about your device.

When drying off after showering or swimming, avoid catching or pulling the sensor on your towel.

Picking the right sensor

If you’re not sure what CGM to get, we have reviews of some of the most popular devices used by people with diabetes.

Head over and read CGM guides to read reviews and for further information on CGMs, or check out the blood glucose monitoring forum to find out what other community members are saying.

Product:

Continuous Glucose Monitoring system

Manufacturer:

Medtronic

Medtronic’s Paradigm REAL-Time Insulin Pump (522/722) was the world’s first with built in CGM functionality.

Medtronic’s Guardian REAL-Time Continuous Glucose Monitoring System is a stand-alone monitor and wireless Minilink transmitter that can be used by any diabetes patient wanting to get a better insight into their

glucose

trends.

The sensors read the
interstitial fluid
readings (known as ISIGs), giving a glucose reading which can be used to adjust insulin doses and to glean a greater insight into any individual’s own body rhythms.

Recording glucose every 10 seconds

All Medtronic’s devices use the same sensor, which records glucose data every 10 seconds and transmits the average reading to update the monitor every 5 minutes.

In this way it is possible for you to see if your body’s sugar levels are moving up, or moving down.

As you can set alarms on the system, it means that you should be able to get advance notice of a

lowering blood sugar

so that you can take action and hopefully avert a hypo.

CGM isn’t cheap!

These are currently very expensive items at around £50 per sensor, each one of which should last about six days.

Generally access through the
NHS
is only for those with relatively severe hypos but as technology and access improves these are likely to become much more common place along with

insulin pump

therapy.

More information

• Call
  Medtronic on 01923 205167

Product:

Guardian REAL-Time

Manufacturer:

Medtronic

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The Guardian REAL-Time system is a stand alone continuous glucose monitoring (CGM) system, from Medtronic, that is designed to be used by people on multiple daily injection therapy.

The Guardian REAL-Time monitor resembles a similar appearance to Medtronic’s MiniMed Paradigm Veo insulin pump but is a little bulky compared with CGM recivers such as the

Dexcom G4 Platinum

or the

Abbott FreeStyle Navigator II

As with other CGMs, the Guardian REAL-Time system is composed of three main elements, a glucose sensor that is attached to the body, a transmitter to attach to the sensor and a monitor that receives data wirelessly from the transmitter.

If you are o, or considering going onto, a Medtronic pump, note that Medtronic pumps include direct integration with Medtronic’s CGM sensors and transmitters and may present a better oiption for you than having a separate CGM system.

Calibration

Calibration of the CGM is made easier if you use, or switch to using, the Bayer Contour NEXT Link blood glucose meter which communicates wirelessly with the Guardian REAL-Time system.

Technical specifications

Monitor

• Dimensions: 51 x 81 x 20 mm
• Monitor weight: Approximately 79 grams (with battery installed)
• Battery: Standard 1.5 V AAA alkaline battery (Energizer brand recommended)
• Communicator range with transmitter: 1.8 m
• Communicator range with blood glucose meter: 1.2 m

MiniLink

• Battery life: 14 days of continuous glucose monitoring

MiniLink charger

• Charger: Completes 40 typical charging operations using a new AAA battery

Product:

FreeStyle Navigator II

Manufacturer:

Abbott

The FreeStyle Navigator II is the successor to Abbott’s FreeStyle Navigator CGM.

The FreeStyle Navigator II features a transmitter (the part you wear on the skin) that is just over 3 by 3 cm and 1 cm deep.

The receiver, which displays the glucose levels, includes a colour screen and range of additional features and alarms to help you monitor your glucose levels.

Features

• Colour screen receiver
• 30m transmission range
• New result every minute
• Trend arrows – showing whether levels are stable, falling/rising or rapidly falling/rising
• Customisable target range
• 5 day sensor life

Sensors

Sensors for the FreeStyle Navigator II are less expensive than the sensors for Abbott’s FreeStyle Libre flash monitoring system, however, each sensor lasts 5 days compared to the 14 day usage available from the FreeStyle Libre sensors.

The sensor insertion device allows the sensors to be added to areas, such as the back of the arm.

Calibration

Calibration should be performed at 1, 2, 10, 24 and 72 hours after sensor insertion to ensure accuracy and functionality. The FreeStyle Navigator II will alert you when a calibration test is required.

Data transfer

Data can be transferred onto a PC via mini USB cable.

However, at time of writing, Abbott’s FreeStyle CoPilot software is not as yet compatible with computer running Windows 8 or Mac operating systems.

Technical specifications

Sensor:

• Measurement range: 1.1 to 27.8 mmol/l
• Sensor life: Up to 5 days
• Operating temperature of sensor: 25°to 40° C

Transmitter:

• Size: 32 x 31 x 11 mm
• Weight: ? (including battery)
• Batteries: One lithium CR2032 coin cell battery
• Battery life: Up to 1 year of normal use
• Wireless range: Up to 3 m
• Waterproof: IPX7 Suitable for water use up to 45 minutes in a depth of 1 m

Receiver:

• Size: 96 x 61 x 16 mm
• Weight: ? (with 2 AAA batteries)
• Data memory: 60 days of normal use
• Batteries: One rechargeable 4.1 V lithium-ion battery
• Battery life: Up to 3 days of normal use
• Test strips: FreeStyle Lite
• Hematocrit: 15 to 65%
• Humidity range: 10% to 93% (non-condensing)

System operating and storage conditions

• Operating temperature: 4°to 40° C
• Storage temperature of system: -10°to 45° C
• Storage temperature of sensor: 3°to 30° C
• Storage temperature of test strips: 4°to 30° C
• Storage temperature of control solution: 2°to 30° C
• Operating and storage altitude: Sea level to 3,048 m

Product:

G4 CGM

Manufacturer:

Dexcom

The G4 Platinum is a

continuous glucose monitor (CGM)

from Dexcom. Released in 2012, the G4 Platinum follows up on the success of the

Seven Plus CGM

The G4 Platinum includes a small sensor which is worn on the body and tracks glucose levels at 5 minute intervals throughout the day with a strong level of accuracy.

The G4 Platinum has a range of customisable alarms to alert when glucose levels are rising or falling quickly or too high or low.

Within the UK, the Dexcom G4 Platinum may be referred to as the Dexcom G4. Whichever name is used, it is the same product.

The Dexcom G4 Platinum is available for use in adults and in children as young as 2 years old.

Features and benefits of the Dexcom G4 Platinum

• Glucose level readings provided every 5 minutes
• High level of accuracy – MARD value of 13% in adults
• Very thin sensor – the diameter of a human hair
• Receiver has a colour screen – helping to interpret results and trends at a glance
• 
  High and low glucose level
  
  alarms
• Alerts how fast glucose levels are rising and falling
• Transmitter able to transmit readings to receiver up to 6m away
• Sensors approved for use for up to 7 days of wearing
• Directed integration with
  
  Animas Vibe insulin pump
  

Modern design

The G4 Platinum receiver boasts a sleek, black modern design that wouldn’t look out of place next to an MP3 player. It is noticeably thinner than the Seven Plus and is around 30% lighter.

The G4 Platinumprovides a graph of your

glucose levels

and does this via a colour screen. The display also includes hour markings making it clearer to read than the Seven Plus.

Increased accuracy

The G4 Platinum is even more accurate than their previous CGM the Seven Plus. The G4 Platinum is over 20% more accurate taking into account all results and 30% more accurate for results below 3.9 mmol/l.

The G4 Platinum provides a MARD value of 13% in adults and 15% in children. MARD stands for mean absolute relative difference and the lower the percentage, the greater the level of accuracy. The G4 Platinum is the first CGM to record a single digit MARD value.

As with other CGM systems, the G4 should be used as a compliment rather than a replacement for

blood glucose testing

The G4 will require calibrating against blood glucose levels once every 12 hours to ensure accuracy.

Integrated with Animas Vibe

If you ow, or are considering owning, the Animas Vibe insulin pump, the good news is that the Dexcom sensors can be integrated directly with the pump. This allows you to view CGM results on the pump itself.

A further advantage is that the Dexcom CGM sensors have been subsidised within the UK when used with the Animas Vibe pump. What this means is that you can get the Dexcom sensors cheaper if you have an Animas Vibe.

Alarms

The G4 Platinum features a number of helpful alarms and alerts, including:

• When glucose levels rise above a selected amount
  
  Default setting 11.1 mmol/l but customisable and can be switched off
• When glucose levels drop too low
  
  Default setting 4.4 mmol/l but customisable and can be switched off
• When glucose levels drop to 3.1 mmol/l
  
  This feature cannot be turned off
• When glucose levels are rising or falling quickly
• If the receiver is out of wireless range from the transmitter
  
  This alert can be switched off

Alarms can be set at a number of levels, ranging from vibrate through soft sound levels to louder levels.

Larger receiver range

The transmitter sits above your skin and transmits the glucose level information to the receiver wirelessly. The transmitter can communicate with the receiver from up to 6 metres away, which is another significant improvement on the previous generation Seven Plus.

How long do the sensors and transmitter battery last for?

The sensors on the G4 can be used for up to 7 days before needing to be replaced. The G4 Platinum receiver will also indicate if a sensor needs replacing soon.

The sensors will often continue working for longer than 7 days and this is seen as an advantage for many people interested in getting a CGM as some CGM sensors cease to work after  the required number of days.

Note that the sensors are only approved for use for 7 days so the additional usage you may get from using them is at your own risk so to speak.

A number of people using the Dexcom sensors have reported good levels of accuracy past the initial 7 days with those users taking care to regularly check the accuracy of the sensors against blood glucose test readings.

The transmitter battery should last for 6 months before the transmitter will need to be replaced.

Technical specifications

Sensor

• Measurement range: 2.2 – 22.2 mmol/L
• Sensor life: Up to 7 days
• Storage temperature: 2° – 25° C
• Storage humidity: 0% – 95% RH

Transmitter

• Dimensions (including sensor pod): 38 x 23 x 13 mm
• Weight (including sensor pod): 11.3g
• Power supply: Silver oxide batteries (not replaceable)
• Moisture protection: IP28: temporary submersion
• Operating temperature: 10° C – 42° C
• Operating humidity: 10% – 95% RH
• Operating altitude: -152 to 3657 meters
• Storage temperature: 0° C – 45° C
• Storage humidity: 10% – 95% RH

Receiver

• Reading frequency Every 5 minutes
• Dimensions: 101 x 46 13 mm
• Weight: 69g
• Power Supply MT21255
• Communication range: 6m
• Memory storage: 30 days of glucose data, 7 days of tech support data
• Re-chargeable battery use: 3 days
• Charging time: 3 hours wall outlet, 5 hours powered USB
• Storage/operating temperature: 0° C – 45° C
• Storage/operating humidity: 10% – 95% RH
• Operating altitude -152 to 3657 meters
• Moisture protection IP22: vertically falling drops

Product:

Seven Plus CGM

Manufacturer:

Dexcom

Dexcom comes to the market with the Seven Plus CGM system which claims to be the GPS of the CGM world, where GPS is a glucose protection system.

CGM is the newest way to monitor

blood glucose levels

and this is one of the few options available in the new technology.

Advances in CGM

As the full title ‘

continuous glucose monitoring

’ states, these little on-body gizmos tell you what your glucose level is (often called blood sugar, but it’s actually glucose).

Dexcom has been in the sensor arena for more than 10 years, and is long in the tooth by comparison with many – showing how new this sector is.

As with other CGM units, the Seven Plus had a transmitter or ‘pod’, which is on the body and includes a sensors that goes just under the skin where it tests interstitial body fluids for glucose.

The pod is both wireless and water-resistant and had an in-built battery that will last a year – so no need for recharging or the chance of it suddenly giving out on you.

Real-time glucose information

There is also a receiver (a handheld that can go in bags or pockets). This has a screen that shows trends and ‘real-time’ glucose level information. Readings are sent from the sensor every five minutes.

Seen in the form of a graph-like line, you can see if your glucose levels are trending up or down, therefore helping you to take action if you need to with a snack to

raise your blood sugar

if you’re heading into hypo.

CGM is meant to do two things – put the power into your hands, and

help you to head off hypos

Putting the power into your hands is by improving your ability to self-manage your diabetes control.

DexCom Data Manager 3 software

The Seven Plus CGM comes with DexCom Data Manager 3 software which in addition to the screen on the receiver can give an even better insight into ways to improve control.

Product:

Enlite Sensor

Manufacturer:

Medtronic

Medtronic’s Enlite Sensor provides the chance to continuously monitor glucose levels via Medtronic insulin pumps and CGM.

If you use a Medtronic insulin pump, the Enlite Sensor is likely to be your first choice if you are looking for CGM functionality as well.

Features

• Direct integration with Medtronic insulin pumps
• Easy insertion with Enlite Serter
• Up to 6 days use

Compatible with a number of systems

Note that the Enlite Sensor, which carries out the measuring of glucose levels, is just one of three main constituent parts of a CGM system. To achieve CGM functionality, the Enlite Sensor is used with the following:

• A transmitter – which sends data from the sensor to the receiver
• A receiver – which displays the data in easy to interpret forms

The Enlite Sensor can be used with a number of transmitters, such as the Guardian 2 Link and the MiniLink transmitters, and a number of receivers such as Medtronic’s MiniMed 640G and MiniMed Paradigm Veo insulin pumps, and the Guardian REAL-Time CGM.

Inserting the sensor

Sensors are relatively easy to insert thanks to the Enlite Serter, a handheld device that deploys the Enlite Sensor with just two presses of a button and minimum fuss. The Enlite Sensor is very quiet and usually painless.

Accuracy

Studies into the accuracy of Enlite Sensors have shown that it has a MARD (Mean Absolute Relative Difference) accuracy of 13.6% which is a strong and reliable level of accuracy.

Studies have also shown the Enlite Sensors to provide a hypoglycemia detection rate of 93.2%.

Product:

FreeStyle Navigator

Manufacturer:

Abbott

The FreeStyle Navigator from Abbott is a Continuous Glucose Monitoring (CGM) device featuring an on-body sensor and transmitter and an off-body receiver.

The FreeStyle Navigator has been superceded by the newer

FreeStyle Navigator II

The sensor is inserted using an insertion device. There is a broad adhesive pad, which makes for a safe, solid base onto which the wireless transmitter attaches.

The sensor and transmitter are usually placed on the stomach or on the back of the upper arm.

Insertion device

The insertion device allows for the sensor to be put in places that other

CGM

inserters may not allow for due to the limitations of handling the insertion device.

This is because some are larger, some require a certain angle for insertio, either of which can lead to some areas being less accessible than others for placement of the sensor and transmitter.

Receiver

The receiver for the FreeStyle Navigator is not an

insulin pump

(as is the case with

Medtronic CGM systems

and the Animas Vibe) but is a stand-alone unit can take blood glucose tests, allowing you to easily calibrate the CGM.

The FreeStyle Navigator requires 4 calibration tests to be taken at approximately 10, 12, 24 and 72 hours after the sensor is inserted.

The CGM will alert you as to when a calibration test is required.

Up to the minute data

The receiver’s screen shows a graph showing your ongoing readings, one every minute. Note that the receiver needs to be within 3m of the transmitter to continue to provide data.

You can see the graph, the current reading in number form (e.g. 8.5mmols/l) and it has an easy to understand arrow that indicates if your

glucose levels

are trending up or down.

Sensor data

• Measurement range: 1.1 to 27.8 mmol/l
• Sensor life: Up to 5 days
• Operating skin surface temperature: 25° to 40° C

Transmitter data

• Size: 52 x 31 x 11 mm
• Weight:
  
  
  14 g (including battery)
• Batteries: One silver oxide 357 HC battery
• Battery life: Approximately 30 days
• Waterproof:
  
  
  Suitable for water use up to 30 minutes in a depth of 1 metre

Receiver data

• Size:
  
  
  63 x 82 x 22 mm
• Weight:
  
  
  99 g (with 2 AAA batteries)
• Batteries:
  
  
  x2 AAA batteries
• Battery life: 60 days of normal use
• Test strips: FreeStyle Lite
• Time for result: 7 seconds
• Hematocrit: 15 to 65%

System operating and storage conditions

• Operating temperature: 4°to 40° C
• Operating and storage altitude: Sea level to 3,048 m

With a blood glucose meter, you use blood to do the test whereas CGM is continuous glucose monitoring.

Continuous glucose monitoring isn’t blood glucose monitoring as the sensors with a CGM machine are placed into your body but not into the bloodstream.

The sensors measure the glucose in your interstitial fluid – the fluid in and around your body’s cells.

The relationship between glucose concentrations in interstitial fluid (ISF) and blood has generated great interest due to the possibility of gaining up to 288 glucose level readings a day without having to do

finger pricks

CGM is less invasive

Basically, CGMs are a less invasive technique for measuring glucose. CGM can be used whether you wear a pump or use

injections
for your

insulin delivery
CGM systems work 24 hours a day and can include alarms to indicate when your glucose levels are too high or too low.

How do I get continuous glucose monitoring (CGM)?

You can buy a continuous glucose monitor but it is first well worth finding out if you qualify for use of a CGM on the NHS.

NICE recommendations

NICE recommends the use of real-time CGM (rt-CGM) for adults and children with type 1 diabetes as part of an integrated package of care that includes education, self-management support, and regular review. The guidelines specify that CGM can be particularly beneficial for:

• Those who have frequent episodes of hypoglycaemia.
• Individuals experiencing severe hypoglycaemia without warning signs.

NICE advises that pregnant women with type 1 diabetes should be offered continuous glucose monitoring to help manage their glucose levels more effectively during pregnancy.

For children and young people under the age of 18 with type 1 diabetes, CGM is recommended under similar criteria to adults, with a strong emphasis on the need for suitable education and support to ensure effective use.

The guidelines covering children are similar and children should be offered continuous glucose monitoring if they are having frequent episodes of severe hypos or having significant problems as a result of impaired

hypo awareness.

Continuous glucose monitoring product guides

Continuous Glucose Monitoring (CGM) is steadily becoming a more in demand way of monitoring diabetes control.

• FreeStyle Libre
• FreeStyle Navigator
• FreeStyle Navigator II
• Dexcom 7+
• Medtronic Elite
• Medtronic Guardian

Is it still blood glucose monitoring?

People may assume CGM is continuous glucose monitoring but it is

not

blood glucose monitoring
, as the sensors used are placed into the body but

not

into the bloodstream.

With a blood glucose meter, you use blood to do the test. With the sensors, they actually measure the glucose in your

interstitial fluid, not your blood.

The CGM system can be used whether you wear a pump wearer or use injections for your insulin delivery.

How can CGM help my diabetes control?

By providing as many as hundreds of readings a day, continuous glucose monitoring can help to provide a very clear idea of how long you are spending with high and low glucose levels.

The data continuous glucose monitoring can provide gives a much more detailed and comprehensive picture of control than

blood glucose testing
can.

One area of uncertainty that commonly exists with standard blood testing is whether highs or lows are taking place when asleep.

Monitoring whilst you sleep

Continuous glucose monitoring has the advantage of being able to provide this information even whilst you’re asleep.

In combination with a detailed food and activity diary, continuous glucose monitoring can offer the chance to make

diet, dosage and lifestyle changes to help reduce the amount of time you spend with

high or low sugar levels

Continuous glucose monitoring has become a particularly in demand method for monitoring diabetes control in mothers to be with

gestational diabetes, as good diabetes control is very important for the development of the baby.

Is CGM as accurate as standard blood glucose monitoring?

The level of glucose in interstitial fluid reacts slower than the level of glucose in the blood.

Therefore, users of a continuous glucose monitoring system should be aware that there is usually a lag of approximately 10 minutes between rises (or drops) in

glucose levels
compared with the blood.

People using a continuous glucose monitoring system are advised to still perform

standard blood glucose tests
to ensure that the continuous glucose monitoring device is giving accurate enough results and before making any treatment corrections.