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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Using the Freestyle Libre Continuous Glucose Monitor on Alternative Sites
Scientific title
The perceived and actual reliability of an alternative Freestyle Libre Continuous Glucose Monitoring application site in people with Type 1 & 2 Diabetes
Secondary ID [1] 295949 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Diabetes Mellitus 309452 0
Flash glucose monitoring 309453 0
Blood glucose monitoring 309454 0
Condition category
Condition code
Metabolic and Endocrine 308293 308293 0 0

Study type
Description of intervention(s) / exposure
Potential participants will be identified and contacted by a diabetes nurse from the Endocrine, Diabetes & Research Centre, and provided with the information sheet. Participants will be recruited from patients attending the diabetes clinic who are currently using a Freestyle Libre or intending to use in the next 3 months. We plan to recruit equal proportions of patients, who are aged 18 years and over, with Type 1 or Type 2 DM, who are using insulin therapy. Participants will not be recruited if they require regular Asprin use as it interferes with interstitial glucose monitoring, or if they have an allergy to medical tape/ sticking plaster and will stop participation if they develop an allergy. Those who express interest will be invited to attend the research centre for 3 visits. The summer student will provide further details, answer any questions and provide an information and consent sheet on the initial visit. After recruitment, three Freestyle Libre sensors will be placed by a summer medical student under the close supervision of a medical practitioner or Clinical Nurse Specialist. Participants will be instructed to regularly scan (at least once) within an 8 hour period for the 14 day trial period (- to upload and store the recorded data. Activity logs (record books) will be continued to be maintained over the 2 week period. The back of upper arm (the comparator) on anterior chest wall, and the flank region posteriorly above the ilium worn simultaneously. The data will be analysed at the end of the 28 days.
Intervention code [1] 312274 0
Treatment: Devices
Comparator / control treatment
The medical student places (and scans) 3 Freestyle sensors at 3 different cites on the body. The comparator is located on the back of the upper arm while the other two are located on the anterior chest wall and the flank region posteriorly above the illium. All three sensors will be used simultaneously. The Freestyle Libre reader allows activation of only one sensor to one reader. The participants will have access to the glucose concentrations and will be advise to only make diabetes management decisions using information from the sensor on the back of their arm.. Data capture from each sensor will be done by the summer student using the reader after 14 days.

Participants will then be asked to return the day after the insertion (and activation) of the sensors and will be asked to fast for 10 hours overnight. They will take their basal insulin dose and any oral medications as usual. An intravenous cannula will be placed to obtain venous blood for comparison with sensor measured glucose. Participants will then undergo testing for four hours following a standard meal, with venous blood collected at 30 minute intervals. Participants will administer an individualised bolus dose of insulin with the meal, based on carbohydrate content. Following this, participants will undertake a standardised period of exercise on a stationary bicycle for 30 minutes. Venous samples will be obtained at 10 minute intervals throughout the exercise and for a further 30 minutes after the end of the exercise. Finally, the skin around the sensors will be cooled for 10 minutes with an ice pack. Skin temperature will be measured.

The sensors will remain in place for the following 14 days. They will be asked to test capillary blood glucose before and three hours after each meal and before bed for the duration of the study. They will also complete a food and activity diary for the 14 days.

At the end of the 14 day period, participants will return to the research centre. The sensors will be removed and the data will be downloaded. Participants will also complete the final interview/questionnaire then we will use qualitative software to identify emerging themes in retaion to people wearing the sensors at the different locations.
Control group

Primary outcome [1] 307265 0
The primary outcome is the proportion of time spent in the range of 4 to 8 mmol/L which will provide an estimation of the mean bias between the comparator site and the two other sites. This will be assessed by the analysis of the data retrieved from each of the sensor downloads.
Timepoint [1] 307265 0
Participants will have 3 visits to the study centre. On the first they will be recruited and 3 sensors will be placed on the back of arm, upper chest and flank. They will be instructed to scan each sensor at least once in an 8 hour period [to upload sensor data] then the sensor will downloaded at the third visit after 14 days. The next day (or soon after) they will return for their second visit for physiological testing. After 14 days they will return for the final rescanning and removal.
Secondary outcome [1] 351306 0
Comparison of sites with venous glucose measurements using a YSI anaylser during meal test and exercise activities. Venous samples will be obtained at 10 minute intervals throughout the moderate intensity 'stationary bicycle' exercise for 30 minutes and for a further 30 minutes after the end of the exercise completion.

Timepoint [1] 351306 0
Participants will be asked to return on the second day (for four hours) after the insertion of the sensors and will be asked to fast for 10 hours. The medical student will insert intravenous cannula and take a fasting blood sample. Participants will then administer their individualised bolus dose of insulin (using a 20% reduction) and given a standard meal.

Key inclusion criteria
Type 1 & 2 diabetes
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Potential participants will not be recruited if they require regular Asprin use as it interferes with interstitial glucose monitoring, or if they have an allergy to medical tape/ sticking plaster and will stop participation if they develop an allergy.

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Participants will be asked questions relating to the acceptablity of wearing the sensors at the alternative sites.
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
For the main analysis the variables (14 day mean blood glucose, 14 day time normalised AUC glucose, proportion of time spent in the range of 4 to 8 mmol/L) will be used for a Bland-Altman limits of agreement plot with estimation of the mean bias between the licensed site (A) and the other two sites and the limits of agreement (95% CI for an individual prediction).

For the secondary analyses where there are multiple measurements per individual mixed linear models will be used. Participants will be treated as a random effect to take account of the correlation between repeated measures on the same participants with fixed effects for the different monitor sites and estimation of bias and individual prediction intervals by device to assess variability.

For these assessments the key sample size consideration is to have sufficient individual participants for stability of estimates of variance. In general terms between 15 and 20 individuals means that variance estimates should be stable.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 20817 0
New Zealand
State/province [1] 20817 0

Funding & Sponsors
Funding source category [1] 300544 0
Name [1] 300544 0
Endocrine Foundation Inc
Address [1] 300544 0
The Endocrine Foundation Incorporated
c/- Endocrine, Diabetes & Research Centre
Wellington Regional Hospital
Capital & Coast District Health Board
Private Bag 7902
Country [1] 300544 0
New Zealand
Primary sponsor type
Wellington Regional Hospital
Riddiford St
Private Bag 7902
New Zealand
Secondary sponsor category [1] 300029 0
Name [1] 300029 0
Address [1] 300029 0
Country [1] 300029 0

Ethics approval
Ethics application status
Ethics committee name [1] 301340 0
Northern Health and Disability Committee
Ethics committee address [1] 301340 0
Phone: 0800 4 38442 (0800 4 Ethic)
(from outside New Zealand: +64 4 819 6877)


Postal address:
Ministry of Health
Health and Disability Ethics Committees
PO Box 5013
Wellington 6140

Street address:
133 Molesworth Street
Wellington 6011
Ethics committee country [1] 301340 0
New Zealand
Date submitted for ethics approval [1] 301340 0
Approval date [1] 301340 0
Ethics approval number [1] 301340 0

Brief summary
Monitoring blood glucose levels is crucial to good control of Diabetes Mellitus (DM) however the inconvenience and discomfort associated with capillary blood glucose testing limits its use. The Freestyle Libre continuous glucose monitor (CGM) is new technology for monitoring subcutaneous interstitial fluid glucose concentration. This technology has recently been introduced to New Zealand and there is considerable interest amongst those with DM.

The manufacturer advises that the sensor device has only been licenced to be sited on the back of the arm, although a few studies have assessed the accuracy and precision of placing the sensor in other body sites. We aim to demonstrate in that using a Freestyle Libre sensor on the chest or flank are comparable with the manufacturer's recommended site on the back of the arm.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 86670 0
A/Prof Jeremy Krebs
Address 86670 0
Endocrine,Diabetes & Research Centre
Wellington Regional Hospital
Private bag 7902
Country 86670 0
New Zealand
Phone 86670 0
Fax 86670 0
Email 86670 0
Contact person for public queries
Name 86671 0
Mr Lindsay McTavish
Address 86671 0
Endocrine,Diabetes & Research Centre
Wellington Regional Hospital
Private bag 7902
Country 86671 0
New Zealand
Phone 86671 0
Fax 86671 0
Email 86671 0
Contact person for scientific queries
Name 86672 0
Dr Rosemary Hall
Address 86672 0
Endocrine,Diabetes & Research Centre
Wellington Regional Hospital
Private bag 7902
Country 86672 0
New Zealand
Phone 86672 0
Fax 86672 0
Email 86672 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Due to privacy reasons, we will not be sharing IPD as we have not requested this.
What supporting documents are/will be available?
Study protocol
Summary results
No Results