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Noninvasive Glucose Measurement
Barbara Deschamp, Timothy Ficarra, Eric Murray
Abstract:
Diabetes mellitus is a metabolic disease that affects over 25 million people in the United States.
Those with the disease need to be have constant awareness of their blood glucose levels, or can suffer
severe consequences. In this paper, we discuss the current methods used by diabetics for blood glucose
measurement, and explore the current implementations of noninvasive glucometry strategies in order to
make a prediction as to which measurement techniques may eventually replace today's blood sampling
methods.
1. Introduction
People with diabetes are tasked with monitoring their blood glucose levels throughout the day
to ensure that these levels remain in a healthy range. Because this measurement is so crucial to their
health, it is important that people can take it safely and easily. The most popular method for measuring
the glucose content of blood is to obtain a blood sample and apply it to a glucometer. As a result,
millions of people are forced to prick the skin in their fingers many times a day in order to draw blood.
However, scientists and engineers have been working on many different approaches to eliminate this
inconvenience by way of noninvasive glucose monitors: sensors that can obtain an accurate reading of
blood glucose levels without the need for a blood sample.
The rest of the paper is outlines as follows. Section 2 provides an overview of what diabetes is
and how it affects people. Section 3 discusses the invasive glucose measurement strategies currently in
use today. In Section 4, the traditional strategies for noninvasive glucose measurement are discussed, as
well as the products currently in development. Section 5 addresses new approaches to noninvasive
glucometry that have recently come to fruition. Finally, Section 6 gives the main conclusions regarding
the feasibility of the methods described in Section 4 and 5.
2. Overview of Diabetes
Diabetes is an autoimmune disease that results from the pancreas losing its ability to provide the
quantity or quality of insulin needed to break down glucose. When carbohydrates enter the digestive
system, they are broken down into glucose that is normally utilized by the cells for energy. However,
insulin is needed for the cells to actually use that glucose. If the pancreas cannot produce the necessary
amount of insulin, excess glucose will build up in the blood stream, causing major consequences.
Two types of diabetes exist. Type I, Insulin Dependent Diabetes Mellitus, accounts for 5-10% of
cases. It usually occurs in childhood as a result of a genetic predisposition and an environmental trigger
(although that trigger is not yet known). The pancreas loses its ability to produce insulin, so diabetics
need to directly inject insulin into their bloodstream. Type II, Non-Insulin Dependent, generally occurs
later in life, as a result of obesity and other factors. In this case, the pancreas is still functioning, but it
cannot meet the body's demands for insulin. Therefore, insulin is taken orally. In some cases, Type II
diabetes is curable with weight loss, diet, and exercise.
If a person's blood sugar is left unregulated, it can lead to a multitude of complications over
time. The combination of the inability to utilize the glucose in the body and the extra work required to
remove the excess glucose can damage many organ. Among these are the eyes, the kidneys, and the
heart. Furthermore, peripheral neuropathy, or nerve damage, can occur all over the body which can
result in amputation. Also, a diabetic has a greater risk of stroke [1].
Diabetes has a profound presence. There are current 25.8 million people in the United States
with diabetes, which accounts for 8.3% of the country's population [1]. An estimated 7 million people
have diabetes but are undiagnosed. In 2010 alone, 1.9 million new cases of diabetes were diagnosed in
people over the age of 20. Furthermore, childhood Type II diabetes is at an all time high, as it is directly
linked to childhood obesity.
Along with the large number of people affected by diabetes are the large health care costs. In
2007, $174 billion was spent treating diagnosed diabetes [1]. $116 billion of that was for direct medical
costs, while another $58 billion was for disability and work loss costs. Minimizing the costs of
diabetes-related health care requires the prevention of major complications through by controlling
blood sugar levels. If a diabetic can maintain his or her blood glucose levels with accurate
measurement and treatment then the risks of complications goes down significantly. Therefore, reliable
glucose measurement methods are needed to keep people healthy and keep health care costs low.
3. Invasive Glucose Measurement
Currently there are two main methods of measuring blood glucose levels. The first is called the
A1C test. A1C is a simple lab test where a small amount of blood is drawn for analysis. The objective
is to determine the average glucose level in a patient over the last three months. These results are an
indication of a person's risk for the medical complications described in Section 2, and are presently the
best way of monitoring a diabetic's health over a long term basis. For diabetics, an A1C test is
recommended at least twice a year. Table 1 shows the relationship between the A1C level and average
glucose level. Although the A1C test is an important indicator of long-term health, diabetics also need
to conduct frequent self tests.
Table 1. A1C Testing Relationship [2].
A1C Level
Average Glucose Level
12
345
11
310
10
275
9
240
8
205
7
170
6
135
Diabetics perform self tests for blood glucose levels on a daily or even hourly basis. These tests
reveal the current amount of glucose present in the blood, so that immediate action can be taken if
necessary. First, the person pricks his or her finger with a lancet to extract a drop of blood. Next, that
blood is placed onto a strip containing glucose sensitive chemicals. An optical meter then analyzes this
sample to provide a numerical reading of the blood glucose level. Depending on the sensor in use,
either the plasma or the whole blood content is used for the sample. For a plasma sensor, a value of 90130 mg/dL is healthy before meals, with a value of less than 180 mg/dL 1 to 2 hours after meals.
Comparatively, for a whole blood value glucometer, 80-120 mg/dL and 170 mg/dL are expected before
and after a meal, respectively [3].
Other self test methods that exist include meters that use alternative site tests, such as upper
arms and forearm, although these are not a replacement for finger pricks. Another method involves
using a Laser to draw blood which was approved by the FDA in 1998. There is also an invasive
continuous monitoring system that exists: The MiniMed monitoring system [4]. This device involves
works by inserting a small plastic catheter under the skin to continually take readings and even inject
insulin automatically.
The concern with these testing methods is that they cause discomfort to those who have to
administer them on a regular basis. The blood sampling methods are an even greater challenge for
people prone to having vasovagal episodes and fainting at the sight of blood. For this reason, many
scientists are looking for a noninvasive alternative, measuring blood glucose levels without direct
contact with blood.
4. Noninvasive Glucose Measurement Strategies
Ideally, diabetics want a noninvasive measurement technique which produces no pain or
discomfort, involves no blood or other bodily fluid obtained by piercing the skin, and does not cause
tissue damage, injury, or deterioration. Despite many attempts by several universities and
manufacturers, no such product has yet to exist. However, many different strategies are being tested
now, including reverse iontophoresis and spectroscopy.
4.1 Reverse Iontophoresis
Reverse iontophoresis is a technique in which electrical current is applied to the skin in order to
extract molecules. The flow of molecules due to the electrical charge is a dominant force which allows
for the movement of neutral molecules in addition to charged ones. This allows for the extraction and
detection of sub-dermal chemicals, such as glucose. As a result of this fact, reverse iontophoresis is a
technique being researched to address the need for a non-invasive glucose measurement solution.
The first commercially available solution for non-invasive glucose measurement was the
GlucoWatch developed my Animas Corporation [5]. The GlucoWatch was a continuous blood glucose
monitor which utilized reverse iontophoresis. Unfortunately, the product was discontinued due to
several problems. First, continuous electrical charge of the watch could cause skin irritation and burns.
Second, the watch was significantly inaccurate in detecting hypoglycemia - 25% of the time the
readings would be as much as 30% inaccurate. Third, the watch still required a blood sample for
calibration and required two hours to become calibrated and ready for use. Animas Corporation
discontinued manufacture and support for the GlucoWatch in 2008.
It has been observed that glucose and lactate levels are metabolically linked [ 6]. This implies
that monitoring lactate levels can help to ascertain the 'healthy functioning' of a patient. The
GlucoWatch was a revolutionary idea which suffered from inaccuracies when glucose measurements
were low. By redesigning the GlucoWatch to also measure lactate levels in addition to glucose levels,
reverse iontophoresis may prove to be the key to non-invasive glucose measurement. This approach is
still in the research stages.
Following the GlucoWatch is the EZ Scan which is built upon the same technology. There are
three major differences between the GlucoWatch and the EZ Scan: 1) the EZ Scan does not conduct
continuous monitoring, 2) the EZ scan does not require a blood test for calibration, and 3) the EZ Scan
is much more accurate. The EZ scan apparatus uses five sensors applied to regions rich in sweat glands
- feet, hands, and forehead. The patient stands on two sensor pads, grips two sensors, and wears a
headband. Over the course of two minutes fifteen tests are conducted - various combinations of DC
voltages and polarities - to determine the current state of the blood glucose level of the patient [7]. The
system requires no calibration or supervision. It is still in developmental stages.
Since the discontinuation of the GlucoWatch there has been no commercially available noninvasive glucose monitoring solution available for diabetics. Presently undergoing clinical trials is a
new transdermal continuous glucose monitor (tCGM) designed by Echo Therapeutics called the
Symphony tCGM [28]. The product has been undergoing clinical trials since 2004 and uses a
proprietary skin preparation system to improve the accuracy of the reverse iontophoresis technique.
The skin preparation system, Prelude, is a tool which uses electricity and feedback algorithms to
painlessly remove the top layer of skin. This layer is mainly comprised of dead skin cells and has been
observed to greatly reduce the accuracy of results in transdermal measurement. Once the skin has been
prepped by the Prelude system, the Symphony sensor is applied to the skin. It is capable of functioning
as a continuous, real-time glucose monitor, and is equipped with a wireless transmitter for sending data
to a monitoring station for analysis.
The FDA acceptance of the GlucoWatch was an important step towards the goal of a noninvasive technique; consequently the inadequacies of the produce were a setback. Fortunately, the
GlucoWatch showed that a solution is possible, and upcoming technologies such as the EZ Scan and
the Symphony tCGM are building upon the failures of the GlucoWatch. With the creation of the
Prelude skin-prep system we have a solution to the inadequacies which killed the GlucoWatch.
Considering the products being developed and the research being conducted, it seems that reverse
iontophoresis is one of the most viable solutions for non-invasive glucose monitoring.
4.2 Spectroscopy
Spectroscopy is the study of the interaction of matter in light. Usually a beam of light is focused
on some area of the body. Depending on what substances are present, the light will react in different
ways. The change in light characteristics are then measured and interpreted. In glucometry, the goal of
spectroscopy is to use light to measure the presence of glucose in a sample or blood or tissue. This
method can be broken down into different subcategories: mid infrared, near infrared spectroscopy,
photo acoustic spectroscopy, and scatter changes. Each of these strategies have different challenges and
obstacles that must be overcome in order to accurately measure the presence of glucose and avoid
interference from water and other materials present in samples.
4.2.1 Near-Infrared Spectroscopy
Near-infrared spectroscopy functions in the .7 – 2.5 micrometer range of the light spectrum. It
explores tissue depths of 1 to 100 millimeters. Near-infrared spectra show less intensity and broader
bands than the mid-infrared region where sharp absorption peaks are typical [9]. Also, reflection
intensity in the near-infrared region is higher than that of mid-infrared.
One method of detecting glucose is near-infrared diffuse reflectance spectroscopy. This method
involves the using a low-energy near-infrared light to illuminate a spot on the body. This light is
partially absorbed and scattered as a result of the chemical characteristics of the skin, before being
reflected back to a detector. The reflectance spectrum of the skin compared to the reflectance of the
instrument calibrator is used to make a prediction as to what amount of glucose is present in the body.
Typically, a graph of the absorbance spectrum of skin contains different spectral signatures for the
different components that are present, including water, fat, protein, and glucose. For example, peaks in
the absorbance will occur for 1448, 1787, 1948, and 2600 nm wavelengths as a result of the absorbance
properties of water. According to Malin et al., the absorbance attributable to glucose is four to five
orders of magnitude less than the absorbance of water, with bands located at 1613, 1689, 1732, 2105,
2273, and 2326 nm [10].
In the experiments done by Malin et al., custom-built scanning near-infrared spectrometers were
used. Using the forearm as the target, the instrument observed the intensity spectra in diffuse
reflectance for the wavelength range 1050-2450 nm, with a spectral sampling interval of 1 nm and a
signal-to-noise ratio at about 90 decibels. These detectors were composed of indium-gallium-arsenide.
In order to obtain consistent results, temperature and forearm position were monitored for each test.
Then, blood samples were taken from each subject as a baseline to compare the spectroscopic results
to.
One of the companies currently working on a commercial glucometer using near-infrared
spectroscopy is Sensys Medical, Inc. However, their upcoming device, the Sensys GTS, has been
redesigned many times to account for various complications in the spectroscopy process [11]. First,
there is the challenge of getting consistent results from a subject's skin. A person's skin is dynamic, as it
experiences changes in texture, color, and temperature. These changes can affect the way the skin
absorbs and reflects light, which in turn will affect the accuracy of the glucose measurement. In order
to overcome these obstacles, Sensys is developing a position system to reduce spectral variation, as
well as coming up with a way of controlling several skin properties. At this point in time their website
is not functional, so no information about the product's release is available.
4.2.2 Mid Infrared Spectroscopy
At first glance, mid-infrared spectroscopy seems like a practical approach to glucose
measurement. Glucose is very effective at absorbing mid-infrared light, and this type of spectroscopic
measurement gets minimal interference from other particles that are present [12]. The human body is
an effective blackbody emitter of mid-IR light at the right spectral region, so the necessary radiation is
therefore already present inside the body near enough to the surface (within 10’s of microns) that its
emission spectrum may be used to measure glucose. The major setback however, is that water has
similar absorption characteristics to glucose in the mid-infrared region, and a sample of blood or other
bodily fluid will contain water. Therefore, instead of just looking at the absorption spectrum for the
glucose, researchers have chosen to use an emission spectroscopy approach for glucose measurement.
The human body acts as a blackbody emitter of mid-infrared light, which means that within the
skin's surface is the radiation necessary to observe the body's emission spectrum. The
emission/absorption characteristics of glucose changes with temperature, so by cooling the outside of
the skin sample where the glucose lies, the glucose absorption spectrum can be observed. This
spectrum can then be superimposed on the normal blackbody emission spectrum of the body to make a
determination about the amount of glucose present.
One company that is developing these mid-infrared glucose sensors is OptiScan Biomedical
Corporation [14]. What OptiScan has developed is an automated, bedside glucose monitoring system
to provide serial blood glucose measurements at 15-minute intervals, called the OptiScanner. Although
the company's original intention was to develop a mid-infrared noninvasive glucometer, this device
requires a 120 mL blood sample to generate a result, while the traditional glucose measuring strips use
between .3 and 1.2 uL [13]. Therefore, this product is actually more invasive than the methods
described in Section 3, and is not marketed towards diabetics, but for critically ill patients who need
constant blood glucose measurement. At this point in time, the company has not announced any plans
to utilize their technology in a non-invasive fashion for diabetics.
4.2.3 Photoacoustic Spectroscopy
Photoacoustic spectroscopy is when a beam of light rapidly heats a target. The optical energy
from the light is converted into acoustic energy, where the beam generates an acoustic pressure wave.
This wave can then be measured with a microphone.
In the work done by MacKenzie et al., a wavelength of 9.676 micrometers was determined to be
the optimum light source for photo acoustic tests [15]. Using this light source, a linear response
correlating to the concentration of glucose in a solution was observed. Specifically, the equation found
was
y = 0.21x – 0.02
where y is the change in the photoacoustic response and x is the glucose concentration. The test data
showed a correlation coefficient of 0.99, indicating that their observations accurately reflected the
equations to model the data.
In later work, MacKenzie et al. developed a special mount containing a piezoelectric transducer
was created for holding a subject's right index finger while a laser pulse was incident on the side of the
finger through an optical fiber [16]. The transducer was able to detect the photoacoustic pulses, which
were administered for 5-second periods at 5-minute intervals. Researchers found that there was a strong
correlation between the photoacoustic measurement and the actual blood glucose concentration,
however, a unique gradient and offset existed for each person being tested. Therefore, a commodity
device using this method would have to be calibrated with the patient in order for it to be safe and
effective.
While accurate glucose readings are possible with this method, the equipment is expensive and
sensitive to environmental changes [17]. Therefore, current research is focused on improving the
repeatability and sensitivity of photoacoustic measurement, as well as the investigation of ideal
detection sites on the human body.
4.2.3 Upcoming Spectroscopy Products
One product that is expected to be released within the next two years is the Scout DS from
VeraLight, Inc. [33]. This product consists of a light source, an optical detector, and a spectrometer,
built into an arm rest with an indicated display. The spectrometer is tuned to measure advanced
glycation end products (AGE). Glycation is the process a cell uses to bind a protein or lipid to glucose,
and is a way for the body to dispose of glucose when insulin is not available. The presence of AGE's
indicates a history of hyperglycemia in the body, which can be used to predict the development of
diabetes. While effective at determining a risk of diabetes and a history of high blood glucose levels,
the Scout DS does not provide the current information about the body's blood glucose levels. It may,
however, replace the blood test used in type 2 diabetes screening.
Another product that shows promising results for the future is the LighTouch Glucose Monitor
from LighTouch Medical, Inc [34]. Currently, LighTouch has 12 patents issued and more pending.
Their sensor projects a specific wavelength of light onto a person's fingertip and detects the wavelength
of the reflected light. Unlike the Scout DS, this device has been designed to replace the finger-pricking
method used by diabetics today, offering the same accuracy in a non-invasive manner. Clinical trials for
the LighTouch sensor began in 1999 with Joslin Diabetes Center of Syracuse, New York. Over the last
decade, the monitor has been continually redesigned in order to improve its speed and accuracy, while
reducing the cost and form-factor. LighTouch is currently in the process of getting FDA approval. The
company plans on releasing their monitor for home use six to nine months after approval. Furthermore,
LighTouch anticipates on releasing modified versions of their sensor for the detection of other blood
analytes.
One last glucose monitor that shows promise is the NBM-200G from OrSense Ltd [35]. This
product is a modified version of an existing product of theirs, the NBM-200MP. The 200MP is a
multipurpose monitor that wraps around the finger, in order to measure hemoglobin, oximetry, and
pulse rate. OrSense's products are based on their proprietary Occlusion Spectroscopy technology. In
this process, a sensor wraps around a person's finger to constrict blood flow. The change in blood
dynamics is used to allow a strong optical response for integrated spectrometer. OrSense currently has
51 patents worldwide, with more than 20 patents pending. The NFM-200G is currently undergoing
clinical trial to test the device's accuracy. As of 2011, this product has been tested on over 450 subjects,
taking measurements over a 24-hour period. Unfortunately, according to OrSense Ltd., “at this stage
the NBM-200G glucose monitor is utilized for investigation and market awareness purpose only” [35].
This statement reveals that the company has made no commitment to getting the product onto the
market as an alternative to the finger-pricking method, despite its feasibility.
4.3 Scatter Changes
Scatter changes involves the refractive index of a sample. Specifically, the increase in the
presence of glucose in a sample will increase the sample's refractive index. Measuring light refraction
against the abdomen has been found to be a very accurate indicator of blood glucose levels. The
problem with scatter change methods is that calibrating a baseline, which is the normal refraction index
of the sample, is very difficult. The process also needs to account for signal shift due to environmental
factors [17]. At the time of this writing, no specific scatter change research publications have been
found.
5. Other Methods
Some recent glucometry methods that deviate from the traditional methods described in the
previous section include: metabolic heat conformation, carbon nanotubes which uses the method of
reverse iontophoresis and fluorescence. The topics were narrowed by focusing on the fluorescence
method. This method was applied by means of a contact lens. The opinion to focus on this topic was
mainly the thought that is the most feasible of the three. The reason is because it was most continuous
and non invasive form.
Metabolic heat conformation is a method of measuring body heat and oxygen supply. This is
achieved by monitoring glucose levels through a sensing device of finger optically and thermally [19].
There is not enough information on this method and it seems that big bulky devices are necessary for
readouts which are not optimal. Carbon nanotubes utilized reverse iontophoresis which we previously
discussed. There come several problems with this method which we have already mentioned.
5.1 Fluorescence
Fluorescence is the emission of light by a substance that has absorbed a different wavelength of
light. It usually has one wavelength absorbed and another longer wavelength emitted which has less
energy. George Gabriel Stokes named this phenomena in which are named after the mineral fluorite.
The most popular reference to these phenomena is usually when an invisible is absorbed and a visible
light is emitted. Examples of this include underwater or aquatic life such as minerals or fish that
appear to glow.
Glucose monitoring can be utilized by fluorescence through means of a boronic acid doped
contact lens [18]. The glucose levels are monitored through the tears. Elevated tear glucose levels were
first demonstrated by Michail et al as early as 1937[24]. It has been found that the glucose in the tears
binds with the boronic acid. The sensor responds to the different concentrations through the diffraction
of light therefore changing fluorescence and wavelength.
The lenses are boron acid doped because it is electron deficient acid and with the presence of
glucose becomes electron rich. These changes of the boron atom can then be noticed by fluorescence
spectral changes in the probe [20]. The spectral changes are measured by a handheld device that
corresponds to blood glucose levels. Experiments have found that results are favorable. This includes a
30 min lag time with the blood glucose levels. This method does not suffer from fluctuations of
ambient light. One sensor that was tested had a glucose testing correlation coefficient of 0.998[19]. It
was also found that most diabetics need corrective lenses due to vision problems caused by the disease.
An experiments have used off the shelf lenses which would require no adjustment in daily life. One
study showed that the lenses were found comfortable even by those who had never worn contact lenses
[23].
Some of the concerns with the design include: pH response, polarity response, leaching,
sensitivity and comfort [21]. The sensitivity has to have a high range which can detect low
concentrations of healthy person the high levels of a diabetic. The comfort of the lens has been
addressed by using off the shelf daily disposable lenses. The pH was addressed and found to be
successful [22]. Also long term research needs to be addressed in the area of biocompatibility and
toxicity [21].
Another concern from the interaction with sugars is leaching which could reduce the intensity
[19]. Leaching is the extraction of certain materials from a carrier into a liquid. One study showed
about an 8% change in the fluorescent intensity due to leaching [19]. Although it is possible to attach
probes to the contact lens polymer which would eliminate any leaching there are other considerations.
It is ideal not to change the lens design so that the optical parameters and physiological characteristics
do not change.
5.2 Most Likely Products for Commercial Use
Two products that are likely be on the market in the near future are the GlucoScope and
Glucoview. The GlucoScope monitor is produced by Visual Pathways Inc. This company is a vision
care diagnostic company based out of Prescott, Arizona. In 2003, they received a federal grant under
the U.S. Department of the Army Medical Research Acquisition Activity and developed a prototype in
2003 [29]. They received a patent in December 2004 for the GlucoScope monitor.
The monitor works by measuring the glucose levels in the fluid of the anterior chamber of the
eye. It is a handheld device that looks like a small pair of binoculars. It uses infrared light to rapidly
measure glucose levels in the aqueous humor of the eye. The glucose concentration in the bloodstream
is directly correlated to the concentration in the aqueous humor. Therefore any variation in the glucose
concentration will cause variations in the index of refraction. Then using interferometry the refractive
index can be measured.
Interferometry is a technique which uses the addition of waves propagating in order to extract
some information. In this device two beams are directed into the eye and caused to interfere. The
interference produces a fringe pattern which is then analyzed. The index of refraction can then be
determined by this analysis. From the index of refraction we can then determine the glucose
concentration which will give us the correlated glucose level that is given by a digital output on the
monitor.
Some of the benefits of the GlucoScope Monitor is that is handheld, portable, non-invasive and
easy to use. The drawback is that it is still in the research and development phase and not commercially
available.
The second product is the Glucoview that is produced by the Sentek Group and licensed from
the University of Pittsburg [27]. The Glucoview is a disposable contact lens which changes color
according to the glucose levels in the tears. The technology is similar to the previous contact
fluorescence method but requires no extra instrumentation. This is achieved by the ground state binding
of glucose to the boronic acid doping agent. The Glucoview uses a Crystalline Colloidal Array
Technology (CCA) in its lens. When the CCA is polymerized within a hydrogel, polymerized CCA
optically reports volume changes experienced by the hydrogel [31]. For instance a red shift indicates
hyperglycemia and a purple shift indicates hypoglycemia. This is due to the fact that the observed
diffraction wavelength is directly related to the spacing between the lattices.
The CCAs are brightly colored because they diffract visible light due to Bragg’s diffraction:
nλ = 2dsinθ where, n is the refractive index of the system, λ is the wavelength of the incident wave and
d is the spacing of the lattice and θ is the glancing angle between the diffracting planes and the incident
light. Bragg diffraction depends on the refractive index of the system and spacing between the
diffracting planes [36].
Benefits of the Glucoview lenses include continuous monitoring of glucose levels. Another
benefit of the lens is that you are able to get easily measurable, quantitative results. It also requires no
instrumentation to collect fluids and doesn’t require any instrumentation to analyze results. It is noninvasive and would be extremely helpful for caretakers of children and elderly. Most diabetics have
vision impairments due to the diabetes which patients may already be used to wearing contacts. A
drawback is that it does not collect data for future analysis. There still needs to be future studies on
calibration, environmental effects and eye irritation.
6. Conclusion
While research into noninvasive glucose measurement has been going on for decades, there is
still no alternative to the finger-pricking method that diabetics depend on. However, there are
promising designs scheduled to make it to market within the next two years.
The product that we feel has the best chance of replacing the traditional finger-pricking method
is the Symphony tCGM and its accompanying skin preparation device, Prelude. It is a variation and
improvement upon a preexisting and established technology, utilizing the only glucose measurement
strategy to ever be commercially accepted, reverse iontophoresis. Echo Therapeutics, the company
developing these two products, has already developed numerous prototypes, and has continued to
perform clinical testing in order to improve the effectiveness of their designs. Therefore, we look
forward to seeing this product on the market at some point in the future, and hopefully it can do the job
it was designed for: replace the invasive finger-pricking method that diabetics must deal with on a daily
basis.
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