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Flash glucose monitoring

What is flash glucose monitoring?

A flash glucose monitor is a small sensor that you wear on your skin. We call it Flash for short. 

It records your glucose (sugar) levels continuously throughout the day and you can access them by scanning the sensor whenever you want to.

The sensor doesn’t actually measure your blood sugar level, it measures the amount of glucose in the fluid that surrounds your body cells – called interstitial fluid. There is a small time delay when checking this fluid, especially after eating or if you're exercising. So your flash glucose monitor result isn't always exactly the same as your finger-prick result. This means you'll still need to do a finger-prick test if you’re thinking of changing your treatment at any point, like if you need to take more insulin or if you're treating a hypo, so you can get the most accurate result.

There is only one flash glucose monitor manufactured at the moment. This is called the Freestyle Libre.


How does it work?

A flash glucose monitor has two parts:

  • A sensor that sits just underneath your skin and measures your sugar levels
  • A reader that you swipe over the sensor to get both your sugar level and the trend of your levels

Each time you scan your sensor, you can access the last eight hours of sugar levels. Flash glucose monitoring also comes with software so you can analyse your results and see patterns in your sugar levels.

You generally wear a sensor for about 14 days, after that you need to insert a new one.

You don’t need to calibrate a flash glucose monitor. 

What’s the difference between flash glucose monitoring and continuous glucose monitoring?

CGM monitors your sugar levels continuously and sends data to your display device (a hand held monitor or pump). So you can set alerts for high, low or rate of change. With flash glucose monitoring, you only get your reading and trends when you scan your sensor.  

Advantages of using a flash glucose monitor

  • You don’t need to do so many finger-prick checks.
  • You can see trends: when your sugar levels are starting to rise or drop, so you can take action earlier.  
  • It can give you more confidence in managing your diabetes as you have more data to base decisions on.
  • You can improve your diabetes management as you have more information about when you’re high and low.
  • You can see what your levels are like at times when you don’t normally test, eg during the night (either by looking back at your own data or scanning someone else’s sensor while they’re asleep).

Disadvantages of using a flash glucose monitor

  • You can’t set an alarm for high or low sugar levels, so it won’t help you recognise a hypo.
  • You can get overloaded with data, which can confuse or worry you.
  • You still need to do some finger-prick checks.
  • You may find wearing the sensor irritating or unsightly.

Using a flash glucose monitor and driving

If you usually monitor your blood sugar levels, you must check them before driving and every two hours during a long journey.

You can use a flash glucose monitor to check your sugar levels before you drive. These rules recently changed, meaning drivers with diabetes now have more choice in how they check their sugar levels. Read more about driving and diabetes.

How can I get it?

On World Diabetes Day (14 November) NHS England announced an end to the flash glucose monitoring postcode lottery.

From April, this life-changing technology will be available on prescription across England to those who meet the criteria – no matter where they live. This is a huge step forward for people with Type 1 diabetes.

At the moment, around 30% of Clinical Commissioning Groups (CCGs) across the UK don’t prescribe flash glucose monitoring (We call it Flash for short). This means thousands of people are being denied access to a technology which could help them more safely manage their diabetes, and reduce the risk of serious complications such as amputation and sight loss.

Excitingly, this announcement should mean an end to the unfair postcode lottery – and to the variations in availability between CCGs which have dogged access to this revolutionary technology.

We know that, unfortunately, this still won’t mean everyone who could benefit from Flash will be able to access it. There are clear criteria that need to be met in order to be eligible for access on the NHS. We’ll continue to work with CCGs to broaden the criteria and fight for everyone who can benefit from Flash to be able to access it on prescription.

This announcement doesn't change the situation in Northern Ireland, Scotland or Wales. In Wales and Northern Ireland Flash is available, using national criteria. You can find more information about the criteria in Northern Ireland on our webpage. Information about criteria in Wales is available in the Health Technology Wales briefing (PDF, 359KB). Availability in Scotland is decided upon by local decision makers. Flash is available in almost all areas.

None of this would've happened without you. We make change happen when we fight together. Find out more about our Flash campaign.


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