Advice
The technology
The technology
The FreeStyle Libre flash glucose monitoring system (Abbott) measures interstitial fluid glucose levels. The system comprises a sensor and a reader. An optional companion app for Android mobile devices is also available.
The sensor is a few centimetres in diameter and is designed to stay in place for 14 days. It is applied to the skin, usually on the upper arm. A thin (0.4 mm), flexible and sterile fibre within the sensor is inserted in the skin to a depth of 5 mm; most people have described this as being painless. The fibre draws interstitial fluid from the muscle into the sensor, where glucose levels are automatically measured every minute and stored at 15-minute intervals for 8 hours. Glucose levels can be seen at any time by scanning the reader over the sensor.
To scan the sensor, the reader is held 1 cm to 4 cm above the sensor for 1 second. Readings can be taken through the wearer's clothes. At each scan, the reader displays current glucose levels, levels over the previous 8 hours, and whether glucose levels are trending upwards or downwards (and how fast). This is called the ambulatory glucose profile. For a full 24 hours of data, users must scan the sensor at least once every 8 hours.
The reader is reusable and has a rechargeable battery that must be charged every 7 days. It also has built-in blood glucose and blood ketone meters, which can be used with FreeStyle Optium blood glucose strips or Optium Beta ketone test strips to test finger-prick blood samples.
As an alternative to using the reader, the sensor can be scanned with a mobile device capable of near-field communication (NFC) and on which the LibreLink companion app has been installed. The LibreLink app can be used on Android mobile devices and has similar features to the reader. It can be used with the LibreLinkUp app to share glucose readings through the LibreView software. LibreView can be used to upload and store data to cloud storage and to view data on mobile devices and web browsers.
FreeStyle Libre does not provide real-time continuous glucose monitoring or a hypoglycaemia alarm.
Innovations
Unlike conventional finger-prick blood glucose testing, FreeStyle Libre uses 'flash' monitoring to measure interstitial fluid glucose levels at regular intervals. Once applied, the sensor allows readings to be taken non-invasively, potentially reducing the number of finger-prick blood glucose tests needed. This avoids the pain caused by finger-prick sampling, which can deter people with diabetes from taking regular measurements.
FreeStyle Libre allows people to see their glucose levels at times when readings are not usually taken, such as overnight. The ambulatory glucose profile allows day-to-day patterns in glucose levels to be seen, which can be used to plan treatment. Unlike continuous glucose monitoring, the factory-calibrated sensor does not need to be calibrated with the user's own blood samples.
Current NHS pathway
NICE has published several guidelines on the frequency of blood glucose and blood ketone level testing for different groups of people with diabetes (see table 1). Education and information on blood glucose monitoring are important parts of each guideline. People with diabetes should to be empowered to self-monitor their blood glucose, and be educated about how to measure it and interpret the results. They should also know what action to take. The guidelines recommend routine monitoring of blood glucose using a finger-prick capillary blood sample. Continuous monitoring of interstitial fluid glucose using a continuous glucose monitor is not recommended for routine use but can be considered for some people (see table 1). No NICE guidelines currently include recommendations for intermittent interstitial fluid glucose monitoring (such as that provided by FreeStyle Libre).
Table 1 Recommendations on frequency of blood glucose and ketone testing
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NICE guidance |
Blood glucose testing |
Continuous glucose monitoring |
Blood ketone testing |
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Test at least 4 times a day, including before each meal and before bed. Test up to 10 times a day in certain circumstances, such as in illness, pregnancy or during sport. Enable testing more than 10 times a day if this is necessary because of the person's lifestyle (for example, driving for a long period of time, undertaking high‑risk activity or occupation, travel). |
Do not offer to adults with type 1 diabetes. Consider for adults with type 1 diabetes who are willing to commit to using continuous glucose monitoring at least 70% of the time and to calibrate as needed, and who have 1 of a number of criteria despite optimised use of insulin therapy and conventional blood glucose monitoring. |
Consider ketone monitoring (blood or urine) during illness. |
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Diabetes (type 1 and type 2) in children and young people: diagnosis and management |
Perform at least 5 capillary blood glucose tests per day. More frequent testing is often needed (for example with physical activity and during intercurrent illness). |
Offer to children and young people with type 1 diabetes who have frequent severe hypoglycaemia, impaired awareness of hypoglycaemia associated with adverse consequences, or the inability to recognise, or communicate about, symptoms of hypoglycaemia. Consider for neonates, infants and pre‑school children, children and young people who have high levels of physical activity, and children and young people who have comorbidities or who are having treatments that can make blood glucose control difficult. Consider its use to help improve blood glucose control in children and young people who continue to have hyperglycaemia despite insulin adjustment and additional support. |
Offer children and young people with type 1 diabetes blood ketone testing strips and a meter, to use if they are ill or have hyperglycaemia. |
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Diabetes in pregnancy: management from preconception to the postnatal period |
Pregnant women who are on a multiple daily insulin injection regimen for type 1, type 2 or gestational diabetes should be advised to test their fasting, pre‑meal, 1‑hour post‑meal and bedtime blood glucose levels daily. Pregnant women who are on diet and exercise therapy, taking oral therapy (with or without diet and exercise therapy) or single dose intermediate acting or long acting insulin for type 2 diabetes or gestational diabetes should be advised to test their fasting and 1‑hour post‑meal blood glucose levels daily |
Do not offer to pregnant women with diabetes. Consider for pregnant women on insulin therapy who have problematic severe hypoglycaemia (with or without impaired awareness of hypoglycaemia), who have unstable blood glucose levels (to minimise variability), or to gain information about variability in blood glucose levels. |
Offer pregnant women with type 1 diabetes blood ketone testing strips and a meter, and advise them to use it and to seek urgent medical advice if they become hyperglycaemic or unwell. |
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Do not routinely offer self-monitoring of blood glucose levels for adults with type 2 diabetes unless the person is on insulin, there is evidence of hypoglycaemic episodes, the person is on medication that may increase their risk of hypoglycaemia while driving or operating machinery or the person is pregnant, or is planning to become pregnant. Consider short-term self-monitoring of blood glucose levels in adults with type 2 diabetes when starting treatment with oral or intravenous corticosteroids or to confirm suspected hypoglycaemia. |
No recommendations. |
No recommendations. |
NICE diagnostics guidance on integrated sensor-augmented pump therapy systems for type 1 diabetes recommends using the MiniMed Paradigm Veo continuous glucose monitoring system for people having episodes of disabling hypoglycaemia despite optimal management of their diabetes using insulin injections. People using this system should use the sensors at least 70% of the time, have a good understanding of the system, and have a structured education programme on diet and lifestyle. They should only continue to use it if they have fewer hypoglycaemic episodes.
NICE is aware of the following CE-marked devices that appear to fulfil a similar function to FreeStyle Libre:
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SugarBEAT (Nemaura Medical; not yet available to the NHS)
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Eversense (Senseonics).
Population, setting and intended user
FreeStyle Libre is intended to be used as an alternative to routine blood glucose monitoring for people aged 4 or over with type 1 or type 2 diabetes, who have multiple daily injections of insulin or who use insulin pumps and are self-managing their diabetes.
Finger-prick blood glucose testing would still be needed:
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during times of rapidly changing glucose levels when interstitial fluid glucose levels may not accurately reflect blood glucose levels
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if FreeStyle Libre shows hypoglycaemia or impending hypoglycaemia
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when symptoms do not match the system readings
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to fulfil Driving and Vehicle Licensing Authority requirements to assess fitness to drive.
The sensor is waterproof in up to 1 metre of water for 30 minutes and can be worn during all daily activities including bathing or showering.
Users would need support and training from diabetes specialist nurses in how to use FreeStyle Libre and interpret the readings. When used by a child aged 4 to 12 years, a caregiver at least 18 years old must supervise, manage and help the child in using the system and interpreting its readings.
The company offers e-learning for healthcare professionals, particularly nurses, in the range of Abbott glucose monitors. Online tutorials and videos are also available on the company website which are aimed at patients learning to use the system.
Technology costs
The commercial retail price (including VAT) of FreeStyle Libre is £57.95 for the reader, which has a 3-year lifespan, and £57.95 for each sensor, which must be replaced every 14 days (this equates to £1,526.02 per year). The company has an application pending for inclusion in the NHS Drug Tariff.
The current retail cost for FreeStyle Optium blood glucose test strips is £15.97 for 50 strips. FreeStyle Optium blood ketone test strips cost £21.36 for 10 strips. The FreeStyle lancets for taking finger-prick blood cost 3.5p each. The LibreLink app can be downloaded for free.
Costs of standard care
A number of different blood glucose meters and test strips are available in the NHS. Blood glucose meters are provided to the patient at no cost, whereas test strips are available on prescription. Meters are generally provided to the NHS at no cost from the company, but test strips and lancets may need to be bought.
Costs for blood glucose monitoring starter kits available through the NHS supply chain range from £14.93 for 1 meter and 10 glucose strips, lancets and a lancing device, to £107.85 for 1 meter and 900 glucose strips and lancets. Costs of blood glucose test strips to the NHS vary according to the meter used but are typically between £7 and £16 for a pack of 50, with bulk-buy savings available and total cost dependent on the meter chosen. Test strip prescribing is currently under review and specific types and quantities available (and therefore costs) may change in future.
Resource consequences
The resource impact of using FreeStyle Libre is uncertain. If adopted, additional costs would be incurred for the purchase of readers and sensors, but the number of blood glucose testing strips needed may be reduced. Additional clinician time may be needed to read and analyse the ambulatory glucose profile reports, although this may be equivalent to the time taken to read and analyse information from the patient's glucose log book. Costs may be saved if using FreeStyle Libre leads to better monitoring and control of glucose levels, and a subsequent reduction in hospital admissions to treat diabetic complications.
A cost-effectiveness analysis, which modelled randomised controlled trial evidence for type 1 diabetes across 6 European countries and Australia, estimated costs for each non-severe hypoglycaemic event averted of around £17 to £25 at 2015 prices, with incremental costs per quality-adjusted life year under published thresholds (Bilir et al. 2016).
Currently, FreeStyle Libre is mainly bought privately by the user, but it is also in use by selected NHS patients.