Flash-UK
The value of flash glucose monitoring with
the FreeStyle Libre 2 system
The FLASH-UK trial demonstrated that intermittently scanned continuous glucose monitoring (isCGM) with the FreeStyle Libre 2 system produced superior clinical benefits versus self-monitoring of blood glucose (SMBG) in people with type 1 diabetes (T1D).
Published in the New England Journal of Medicine by Leelarathna et al, FLASH-UK was an independent, multi-centre, parallel-group randomised controlled trial (RCT).
The FLASH-UK trial compared the efficacy of isCGM with the FreeStyle Libre 2 system versus traditional SMBG. Use of the FreeStyle Libre 2 system resulted in significantly lower glycated haemoglobin (HbA1c or A1c) levels and increased treatment satisfaction in individuals with T1D and elevated HbA1c.
FLASH-UK was an open-label, parallel-group, RCT conducted at seven specialist diabetes clinics and one primary care centre in the UK. Participants were randomly assigned (1:1) to undergo isCGM with the FreeStyle Libre 2 system or to monitor their own blood glucose levels with the use of finger prick testing. Abbott played no part in the design, funding or conduct of the trial.
Key Inclusion criteria** 
Key exclusion criteria**
Primary outcomeKey secondary outcomes.png)
SD: standard deviation; MDI: multiple daily injections; CSII: continuous subcutaneous insulin infusion
*The body mass index is the weight in kilograms divided by the square of the height in metres.
†Gold scores range from 1 to 7, with higher scores indicating impaired awareness of hypoglycaemia.
‡Clarke scores range from 0 to 7, with higher scores indicating impaired awareness of hypoglycaemia.
Primary and secondary outcomes
SMBG, self-monitoring of blood glucose
FSL2 : FreeStyle Libre 2 system
* Odds ratio values greater than 1 favored the intervention group. Between-group differences are expressed in percentage points.
A video featuring Professor Mark Evans (Co-author of the FLASH-UK study), who talks about the reduction of HbA1c in the FLASH-UK study.
CGM, continuous glucose monitoring; isCGM, intermittently scanned continuous glucose monitoring; SMBG, self-monitoring of blood glucose.
*Prior to group allocation, all subjects underwent blinded CGM assessment (FreeStyle Libre Pro§). At 24 weeks, those randomised to SMBG underwent a second period of blinded CGM assessment with FreeStyle Libre Pro; the data was compared to the isCGM data from the same 2-week period from the group allocated to FreeStyle Libre 2 system.
†Adjusted Mean Difference
‡Rounded value based on actual improvement of 130 minutes (95% CI, 68 to 192) per day
A video featuring Dr Emma Wilmot (Site Principal Investigator), who talks about TIR in the FLASH-UK study.
*Prior to group allocation, all subjects underwent blinded CGM assessment (FreeStyle Libre Pro§). At 24 weeks, those randomised to SMBG underwent a second period of blinded CGM assessment with FreeStyle Libre Pro; the data was compared to the isCGM data from the same 2-week period from the group allocated to FreeStyle Libre 2 system.
†Adjusted Mean Difference
A video featuring Dr Emma Wilmot (Site Principal Investigator), who talks about the reduction of hypoglycaemia in the FLASH-UK study.
*Prior to group allocation, all subjects underwent blinded CGM assessment (FreeStyle Libre Pro§). At 24 weeks, those randomised to SMBG underwent a second period of blinded CGM assessment with FreeStyle Libre Pro§; the data was compared to the isCGM data from the same 2-week period from the group allocated to FreeStyle Libre 2 system.
†Adjusted Mean Difference
‡Rounded value based on actual improvement of 86 minutes (95% CI, 13–158) per day.
The number of reported adverse events during the observation period was low and comparable across both study arms.
92.1% mean sensor use
during last two weeks1
11 scans/day
on average1
➤ Participants were aware of the trial-group assignments.
➤ Nearly all the participants were white.
➤ The trial took place during the Covid-19 pandemic and some participants had virtual visits with the option of performing capillary blood tests to determine the glycated haemoglobin level at home.
CGM: continuous glucose monitoring; TIR: Time in Range; isCGM: intermittently scanned continuous glucose monitoring
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The FLASH-UK study has proven the clinical efficacy of using the FreeStyle Libre 2 system in people
with T1D on multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII)1 .
FreeStyle Libre 2 system significantly reduced HbA1c at 24 weeks, compared to SMBG
FreeStyle Libre 2 system significantly increased Time in Range
FreeStyle Libre 2 system significantly decreased time spent in hypoglycaemia
FreeStyle Libre 2 system significantly decreased time spent in hyperglycaemia
FreeStyle Libre 2 system improved patient satisfaction
Patients using the FreeStyle Libre 2 system had a high adherence to
glucose monitoring with a low incidence of sensor-related adverse events
See a summary of clinical evidence supporting the use of the FreeStyle Libre 2 system here
** A comprehensive list of criteria can be found in the supplement of the publication.1
§ FreeStyle Libre Pro, no longer for sale in EU & UK.
Reference
1.Leelarathna L, Evans ML, Neupane S, et al. Intermittently scanned continuous glucose monitoring for Type 1 diabetes. N Engl J Med. 2022;387(16):1477-1487. doi:10.1056/NEJMoa2205650
2.Battelino T, Danne T, Bergenstal RM, et al. Clinical targets for continuous glucose monitoring data interpretation: Recommendations from the International Consensus on Time in Range. Diabetes Care. 2019;42(8):1593-1603. doi:10.2337/dci19-0028
3.Beck RW, Riddlesworth T, Ruedy K, et al. Effect of continuous glucose monitoring on glycemic control in adults with Type 1 diabetes using insulin injections: The DIAMOND randomized clinical trial. JAMA. 2017;317(4):371-378. doi:10.1001/jama.2016.19975
4.Lind M, Polonsky W, Hirsch IB, et al. Continuous glucose monitoring vs conventional therapy for glycemic control in adults with Type 1 diabetes treated with multiple daily insulin injections: The GOLD randomized clinical trial. JAMA. 2017;317(4):379-387. doi:10.1001/jama.2016.19976
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