Latest studies of a 'flash' glucose monitoring system, Abbott's
Freestyle Libre, show it as an adequate replacement for
finger-prick glucose testing. And safe and accurate when used by
children and young people with diabetes (4-17 years).
The Libre system comprises a small round glucose sensor worn for
up to 14 days on the back of the upper arm and a scanner device
that the patient waves over the sensor to obtain a reading of
glucose concentrations in the interstitial fluid. The scans display
both historical and current glucose trends. Glucose measurements
can be taken through clothing, and the sensor is water-resistant
and can be worn while swimming and bathing.
The system measures interstitial tissue glucose levels every
minute via a disposable round sensor about the size of a $1 coin,
with a small catheter inserted under the skin, worn on the back of
the upper arm for up to 14 days. The wearer scans the sensor with a
reader, which generates a real-time glucose test, an 8-hour trend
history, and the direction glucose is heading.
However, finger-prick measurements are still required when blood
glucose levels are rapidly changing, since interstitial fluid
glucose levels may not accurately reflect the current blood
Finger-prick testing is also advised when the system reports
hypoglycemia or impending hypoglycemia or when the patient's
symptoms don't match the device's readings.
Latest studies used a blinded version of the FreeStyle Libre
system in the current prospective, single-arm study, involving 89
children aged 4 to 17 years with type 1 diabetes in nine UK
diabetes centers. Participants were asked to perform four capillary
blood glucose tests daily, each immediately followed by a sensor
reading. The data were unmasked on the third and final visit, at 12
to 15 days.
Study results were released online on January 31 in theArchives
of Disease in Childhoodby Julie Edge, MB ChB, paediatric
endocrinology and diabetes, Oxford Children's Hospital, United
Kingdom, and colleagues.
Results after 14 days show that overall the mean absolute
relative difference between blood glucose measurements and the
Freestyle Libre sensor was 13.9%, with 83.8% of results in zone A
and 99.4% in zones A or B of the "consensus error grid," a model
developed to assess continuous glucose monitoring accuracy.
Unlike current CGM devices, the Libre was approved as an
alternative to routine blood glucose monitoring, and diabetes
patients can use the results to guide therapeutic decisions.
The system was granted a CE Mark in Europe in 2014 as a
replacement for finger-prick glucose monitoring in people with
diabetes (any type) down to 4 years of age and is now available in
28 countries, with almost 200,000 users globally.
"The FreeStyle Libre System is not a CGM device - with FreeStyle
Libre Abbott has developed a new category, of flash glucose
monitoring," a company spokesperson said.
CGM and Finger-prick Testing Can Be Problematic in
Dr Edge and colleagues note in their paper that monitoring of
blood glucose levels in children and adolescents by finger-prick
testing can be challenging, due to unpredictable and increased
frequency of food intake, variable patterns of physical activity,
and psychological and hormonal changes during adolescence, among
other issues. This in turn can lead to greater glycemic
variability, wider glycemic excursions, and more frequent
hypoglycemia than seen in adults.
And monitoring glucose via CGM is problematic in children and
adolescents too, for a number of reasons, the team notes. The
FreeStyle Libre System "potentially resolves many of the issues
that affect adherence with CGM," Dr Edge and colleagues point
Type 1 diabetes exchange data indicate that the majority
(>75%) of children/young people with diabetes do not meet
International Society for Paediatric and Adolescent
Diabetes/American Diabetes Association guidelines for glycaemic
control (glycated haemoglobin <58 mmol/mol (7.5%)).
Results of latest study published in the
Archives of Disease in Children