What is Flash Glucose Sensing (Libre)?

“What is Flash Glucose Sensing/Monitoring (Libre)?”


Libre reader following a 'flash'

Libre reader following a ‘flash’


Flash Glucose Sensing (FGS) is located under “CGM” simply because it uses a sensor and displays trends. It has its own page because it is not CGM but is more than blood glucose testing. Abbott describes their FreeStyle Libre as a replacement for routine fingerstick blood glucose measurements but in the diabetes community, Libre is being talked about as a potentially cheaper alternative to CGM. Both measure the glucose in interstitial fluid but the Libre sensor cannot transmit and therefore will not alert you to low or high glucose levels until you ‘flash’ the sensor.

The Libre system includes a sensor which is worn for up to 14 days, and a handset which the user scans over the sensor to obtain a reading. The reading also shows a trace for the last 8 hours and usually a direction arrow showing whether the glucose reading is stable, rising, rising fast, falling or falling fast. The handset includes a smart FreeStyle Optium blood glucose meter and blood ketone meter.

Abbott markets Libre as a replacement for fingerstick blood glucose monitoring, but note that the Abbott FreeStyle Libre UK website says:

“A finger prick test using a blood glucose meter is required

  • during times of rapidly changing glucose levels when interstitial fluid glucose levels may not accurately reflect blood glucose levels or
  • if hypoglycaemia or impending hypoglycaemia is reported by the System or
  • when symptoms do not match the System readings.”
    (INPUT’s highlighting)

Please note: you will still need to do fingerstick blood tests prior to and during driving to meet DVLA requirements. 

Emma, 20’s, said “It has reignited my interest in my blood sugars. I’ve always been frustrated by finger prick tests because you don’t actually know what the reading means. Am I stable? Going up? Plummeting down? Now I know 😀 I already can’t imagine life without it.”

Useful publications about Flash Glucose Monitoring (Libre)

The Edinburgh Centre for Endocrinology & Diabetes has produced a helpful guide to using Libre data to improve glucose control in type 1 diabetes – click here

NICE Medtech Innovation Briefing (MIB) published July 2017 – link

MIBs are Objective information on device and diagnostic technologies to aid local decision-making by clinicians, managers and procurement professionals. The information provided includes a description of the technology, how it’s used and its potential role in the treatment pathway. This is not the same as NICE guidance, and does not have to be acted on by clinicians, managers or commissioners.

Diabetes UK consensus guideline to Flash glucose monitoring – published August 2017
“We have developed these recommendations for the use of Flash GM in the NHS, jointly with other diabetes organisations representing people with diabetes and clinicians. We recognise that there is need for further research and audit to determine a full picture of the benefits and limitations of the technology to the NHS and people with diabetes. These recommendations are based on the best currently available clinical and scientific evidence as well as experiences from people living with diabetes using this technology.”

See our Research page for research and articles about Libre.

Libre website & webshop (be sure to tick the VAT exemption box)

To join the chat about Libre, have a look at the Facebook group

Read our other CGM pages