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Flash monitoring (Freestyle Libre)

A flash glucose monitoring system measures your sugar (glucose) levels continuously throughout the day.

It can help you and your diabetes team see:

  • if your sugar levels are going up or down
  • how your sugar levels change over time
  • the past 8 hours so you can see what happens to your levels when you sleep at night

Flash does not actually measure your blood sugar levels. It measures the amount of sugar in the fluid under your skin, called interstitial fluid.

Interstitial fluid sugar readings are a few minutes behind your blood sugar levels. This means you'll still need to do finger-prick checks every now and then.

The measurements can help you and your diabetes team make decisions about your treatment and any adjustments you need to make.

A flash system is made up of:

  • a sensor you stick to your arm (about the size of a £2 coin)
  • a reader – a small device you use to scan the sensor to see your sugar levels

You can also use a smartphone app to scan the sensor.

Sensors usually last for 14 days.

You still need to do some finger-prick tests, particularly when you drive or have a hypo.

Unlike a continuous glucose monitoring (CGM) system, flash does not have an alarm for hypo or hyper warnings.

With a CGM, your sugar levels are always visible on the screen of your receiver. With flash, you use the reader to scan the sensor when you want to see your levels.

How to get a flash system

The only flash system available is the Abbott Freestyle Libre.

Getting a flash system on the NHS

As of November 2017, the Freestyle Libre is available on the NHS in some areas (depending on local approval).

You must meet certain criteria to get it on prescription, such as testing your blood glucose more than 8 times a day and having disabling hypos.

Ask your diabetes team if it's available where you live. Access is different around the UK.

Diabetes UK has more about flash glucose monitoring systems.

You can buy a flash system yourself

As a rough guide, it costs around:

  • £150 for a starter pack (reader and 2 sensors)
  • £50 for a sensor
  • £50 for a reader

Speak to your diabetes team if you're thinking of buying a Freestyle Libre.

Page last reviewed: 14 May 2018
Next review due: 14 May 2021