Continuous glucose monitoring systems


Systems (from left to right):  Freestyle Libre, Medtronic (with insulin pump), Dexcom

Continuous glucose monitoring (CGM) systems provide 'real-time' information by measuring glucose levels every few minutes.  This provides a trace (see image below) as well as information on whether glucose levels are stable, rising or falling.  This offers more detail than a single 'finger-prick' glucose value and use of CGM has been associated with improved glucose control.  Please note that CGM systems are not funded by the NHS in Scotland - anyone wishing to use these systems must purchase them, using their own funds, directly from the manufacturers.  The situation has recently changed (February 2018) with respect to the Freestyle Libre system in Lothian and further information is provided below.

Click here to be taken to the JDRF website section on CGM.

  An example of a CGM trace

An example of a CGM trace

CGM systems

Freestyle Libre

UPDATE (FEBRUARY 8th 2018):  The Lothian formulary committee informed us today that it approved the Freestyle Libre for restricted use at its meeting on 24th January.  The criteria for accessing NHS-funded Libre sensors are listed below.


Flash Glucose Monitoring can be considered in people who:

1. Use intensive insulin therapy (typically 4 or more injections a day or an insulin pump); and

2. Agree to attend a locally provided Flash Glucose Monitoring education session; and

3. Agree to scan glucose levels no less than six times per day; and

4. Agree to share glucose data with their diabetes clinic;

5. have attended a recognised diabetes structured education programme. And/or clinical team are satisfied that the person (or carer) has required knowledge/skills to self-manage diabetes.


The formulary committee has specified that advice to start Freestyle Libre must come from a hospital diabetes specialist, so we are asking people with diabetes not to approach their GPs directly.  Once a hospital specialist has recommended the Libre, general practitioners will take over prescribing the sensors.  Over the next 6-8 weeks the diabetes clinics in Lothian will write out to adults with type 1 diabetes to explain how to access the education required before the Libre sensors can be prescribed.  The Scottish Diabetes Group and the Lothian Formulary have been very clear that the need for education applies even when people have already been self-funding their own Libres.  We understand that people will be anxious to access this technology as soon as possible but we must ask you to bear with us as there are literally thousands of potentially eligible people whom we have to write to and we will have to set up many group education sessions.  Education for paediatric patients may need to be done on a one to one basis.  Further information for people with diabetes under the age of 18 can be obtained at their next clinic appointment Given the number of people eligible to start the Libre in the coming months, telephone and letter enquiries during this time risk overwhelming our clinical and administrative staff and taking us away from the more important task of arranging the education which will allow access to funded Libre sensors.



Freestyle Libre

The Freestyle Libre is not technically a 'CGM' system as it does not continuously display glucose levels but will display a current glucose level (with a trend arrow) when the reader device is swiped over the sensor.  It is also able to produce 24 hour glucose traces (like the example above), so long as the sensor is scanned at least every 8 hours.  The major advantages of the Libre system are that it does not require calibration with 'finger prick' capillary blood glucose levels and is significantly less expensive than Dexcom and Medtronic systems.  The disadvantages are that it cannot alarm, to warn of impending high or low glucose levels, and it cannot communicate with insulin pumps.  Click here to be taken to the official Libre website or click here for the RIE Libre resource.

LibreLink:  an iOS (iPhone 7 and above) / android app which turns your phone into a Libre reader .  One major benefit of this app is that it will work with Libreview or Diasend app to directly upload all your glucose data which can be shared with the clinic, should you chose to do so.

How to link your Libre Link and Diasend apps on android phones

Find out more about LibreView here

Medtronic Guardian

Medtronic CGM systems can be used by patients on multiple daily injections but are most useful for those using Medtronic insulin pumps, as the sensor can communicate directly with the pump.  The major advantage of this is the ability to take advantage of 'Low glucose suspend' and 'SmartGuard' features, which stop the infusion of insulin overnight if glucose levels fall below a pre-defined threshold.  Alarms can be set to inform users when their glucose levels rise above or fall below acceptable limits.  These devices require calibration with 'finger prick' glucose tests.  The annual cost of Medtronic's CGM system is approximately £3000.  Click here to be taken to the official Medtronic website.


The Dexcom G5 system can be used in patients using multiple daily injections or pumps.  The G5 will transmit glucose levels to Animas insulin pumps but does not have low glucose suspend features.  The Dexcom G5 is capable of transmitting results to iphones and, like Medtronic's device, will alarm when glucose levels fall below or rise above personally set limits.  This device also requires regular calibration with 'finger prick' glucose values.  The annual cost of the Dexcom system is around £3000.  Click here to be taken to the official Dexcom site.


If you are considering using a CGM system, please contact your diabetes specialist for advice.  Deriving the maximum benefit from these systems requires appropriate education on how best to use them and also requires regular reflection and feedback on the huge amounts of information such systems provide.  

CGM guide

We have produced a brief guide to using CGM systems - click on the image below to download the pdf: