Is Interstitial Fluid Glucose Monitoring Replacing Finger Prick Tests?

This essay critically evaluates the argument that interstitial fluid glucose monitoring signals the end of finger-prick blood glucose monitoring for diabetes management. It highlights that while interstitial fluid glucose monitoring offers a convenient and continuous method for tracking glucose levels, its accuracy and real-time data acquisition are not as reliable as finger-prick tests. The essay discusses the importance of insulin in regulating blood glucose levels and the role of self-monitoring in diabetes management. It references the use of continuous glucose monitors and flash monitoring systems, emphasizing the delayed readings and potential inaccuracies associated with interstitial fluid glucose measurements. The ambulatory glucose profile is mentioned as a tool for interpreting data from continuous glucose monitors, providing a clearer visualization of glucose trends. The essay concludes that both methods have their advantages and limitations, and the most effective approach involves utilizing both interstitial fluid glucose monitoring and finger-prick tests to ensure accurate and comprehensive glucose level management, ultimately preventing diabetes-related complications.

‘Interstitial fluid glucose monitoring signals the end of finger-prick blood glucose monitoring’
‘Interstitial fluid glucose monitoring signals the end of finger-prick blood glucose monitoring’, this
proposed argument is quite misleading as it suggests that the monitoring of interstitial fluid glucose
would be a more effective method for diabetic people than finger pricking. Diabetes is a metabolic
disorder where the body is unable to control blood glucose concentration levels due to an insulin
deficiency or inability to respond to insulin (Toole and Toole, 2015) and in the UK there are an
estimated 3.8 million people who are diabetic (Diabetes UK, 2019). There are two types of diabetes;
type 1 which is insulin-dependent and type 2 which is insulin-independent, both forms of the disease
require the individual to monitor their sugar glucose levels. Individuals need to regulate their
carbohydrate intake and partake in regular exercise to maintain regular sugar glucose levels and
inject insulin. Insulin is a hormone in the body that is significant to the functionality of the body as it
promotes ‘the storage of metabolites in peripheral stores’ and it also ‘promotes body gain by
stimulating protein and fat synthesis (Tandfonline.com, 2019). To ensure the maintenance of blood
sugar levels diabetic people can self check this through doing a finger prick test or with a continuous
glucose monitor. The initiated argument of interstitial fluid glucose signalling the end of the use of
the finger prick test to monitor blood glucose levels is inaccurate as research suggests that both
methods should ideally be used hand in hand. The self- monitoring of blood glucose was argued as
being ‘one of the most important advancements in diabetes management since the invention of
insulin in 1970’ (Cengiz and Tamborlane, 2009), and the recommendation of using both monitoring
methods together is due to the readings from the continuous glucose monitors not being accurate
and delayed. This is as the interstitial glucose differs from the blood glucose, when investigated it
showed that as glucose levels increased the interstitial fluid glucose readings were lower than the
blood glucose readings from the finger prick test (Medtronicdiabetes.com, 2019) - the readings from
the contrasting methods rarely match so utilising both methods would give greater accuracy in
readings.
Interstitial fluid glucose monitoring may be a preferred method for diabetics as it offers a non-
invasive method to continuously measure the glucose levels within their interstitial fluid. Interstitial
fluid is a thin layer of fluid that surrounds the body’s cells and monitors glucose levels in people with
diabetes (Freestylediabetes.co.uk, 2019). Either flash monitoring or continuous glucose monitoring
systems can be utilised as methods to continuously monitor sugar levels for those with diabetes.
However, the difference between the two monitoring systems is that the continuous glucose
monitor offers signals for when sugar levels are high or low which could act as a sign for
hyperglycaemia or hypoglycaemia thus allowing preventative methods to be taken before those risks
occur. Additionally, continuous glucose monitoring offers readings of sugar glucose levels on the
screen of the device whilst with the flash monitor the reader is used to scan the sensor when sugar
levels are needed to be seen (nhs.uk, 2019). The diagnostic method of interstitial fluid glucose
monitoring allows those with diabetes to see trends in their sugar levels; thus allowing them to find
any triggers to their glucose fluctuations. For example, the FreeStyle Libre Pro system is a device
designed to aid those with type 1 diabetes to monitor their glucose levels. The device provides a
more convenient, discreet and easy to use method to glucose monitoring (Freestylediabetes.co.uk,
2019), the sensor is applied to the back of the upper arm of the individual and a fibre is then inserted
under the skin. To obtain readings of glucose concentration levels the individual scans the reader
over the sensor which then provides readings from ‘8 hours of glucose reading’. The location
in which the sensor is placed on the body, upper arm, is highly important as it was found that

inserting the flash glucose monitor here would result in more accurate readings when compared to
the monitor being on the abdomen which had less reliability in readings (Mancini et al., 2018).
Those who contend for the conjunction of use of finger prick glucose monitoring and interstitial fluid
glucose monitoring argue that a significant assurance of accuracy in readings would be guaranteed.
As measurements solely dependent on interstitial fluid glucose monitoring/ continuous glucose
monitoring would provide patients with limited data regarding the change in glucose levels in real-
time due to delayed reading. It was found in a clinical trial that continuous glucose monitoring is not
as reliable as assumed, as interstitial fluid glucose monitoring device manufacturers ‘use mean
absolute relative difference to describe performance’(JDRF, the type 1 diabetes charity, 2019) and
it’s calculated differently than blood glucose meter accuracy. The trial conducted found that ‘the
mean absolute relative difference was 12.2% with 95% real- time data…these data suggest that point
accuracy of interstitial glucose monitoring cannot replace blood glucose level measurements’ (van
Hooijdonk et al., 2015). ‘MARD is a reported metric for average accuracy but does not reflect any
non-linear performance over the complete glucose range, nor does it provide any information about
the precision of the system on which it reports’(Ajjan et al., 2018). From the definition provided and
data from the trial this allows us to conclude that the point of accuracy of interstitial fluid glucose
monitors doesn’t meet the same standard of readings from finger pricking blood glucose. This
doesn’t comprise its effectiveness but rather challenges the proposed essay title of it signalling the
end of finger-prick blood glucose monitoring.
The data obtained from the readings of continuous glucose monitors can be interpreted by using
the ambulatory glucose profile which provides a simpler and clearer visualization of glucose levels in
the blood- presenting trends more evidently for users to read. The ambulatory glucose profile is a
single curve graph which was developed by Roger Mazze, the graph shows an average of the data
collected from the FreeStyle Libre Pro system or other continuous glucose monitors (Hammond,
2019). The data from the graph provides a 24 hour period outlook on the readings of an individual to
portray and give them the ability to view any fluctuations in glucose levels in blood thus reducing the
risks of hyperglycaemia or hypoglycaemia (Evans, 2019).
Overall, the argument stated that ‘interstitial fluid glucose monitoring signals the end of finger-prick
blood glucose monitoring’ is equivocal as both methods of measuring glucose levels in the body
ultimately correspond to the aim of supporting people who suffer from diabetes to become more
aware of their blood glucose levels thus preventing complications such as heart disease, stroke,
kidney disease or nerve damage from occurring. The issue that arises when approaching this
argument is that the measurement of interstitial fluid glucose instead of directly measuring the
blood glucose; it obstructs the individual with the monitor from obtaining the accurate readings in
which they require. Everything considered I can conclude that the monitoring of interstitial fluid
glucose doesn’t prompt the end of the use of finger pricking. Although the prospect of the
advancement of technology in helping those who suffer from diseases such as diabetes proves to be
compelling, in this case, one method shouldn’t dismiss the efficacy of the other as when both are
utilised together this guarantees great functionality and provides accurate results.

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