US Pharm. 2013;38(10):8-11.
Diabetes mellitus is an endemic medical condition in the
United States. The CDC estimates that 8.3% of U.S. citizens are
affected, including 18.8 million who are diagnosed and perhaps another 7
million who are not yet diagnosed.1 Diabetes is the seventh
leading cause of death in the U.S., a major cause of heart disease and
stroke, and the leading cause of renal failure, nontraumatic amputation
of the lower limbs, and new cases of blindness among U.S. adults.1
Self-Monitoring of Blood Glucose
Before the advent of blood glucose testing, patients who
wished to monitor blood glucose used urine test sticks (e.g., Diastix,
Clinistix), urine testing paper (e.g., Tes-Tape), or urine testing
tablets (e.g., Clinitest). These tests became outmoded as blood glucose
meters were marketed in the late 1970s and thereafter.2 The advent of self-monitoring of blood glucose
(SMBG) allowed patients for the first time to exert tight control of
their diabetes. They were better able to balance diet, exercise,
insulin, and oral medications to keep their blood glucose at safe
levels. This tight control helps prevent the deadly sequelae that are
inevitable with hyperglycemia and hypoglycemia.
General Tips for Patients
When patients inquire about SMBG, pharmacists can provide a set of general instructions to help them achieve success.3
The first thing a patient should do after purchasing a meter is to read
the instruction booklet thoroughly. Many people do not read the
instructions before proceeding with use of a newly purchased product.
They may be fully able to rely on their intuitive skills to assemble a
bookcase or use a new kitchen appliance, as the consequences of misuse
in these cases are generally harmless. That is not the case with blood
glucose meters. Patients who misuse a blood glucose meter may deliver a
large overdose or significant underdose of insulin, either of which can
be deadly. Further, being fully familiar with one type of meter does not
mean a patient will be able to use a new meter without first reading
the manual for it. In addition to reading the instructions thoroughly,
patients should also be advised to locate the toll-free number that they
can call for further information.
A common question about blood glucose meters concerns test
strips and whether one brand of strips can be used in another
manufacturer’s meter. Patients may also ask if any other test strips can
be used with an older meter when the recommended strips are no longer
available. The answers to both of these questions is almost always no.
Other questions about strips are driven by cost
considerations. Blood glucose test strips are one of the most expensive
components of diabetes care, costing as much as $1.60 each (e.g.,
FreeStyle InsuLinx Strips).4 Testing five times daily becomes
an expensive proposition, costing $8 daily for those strips, or
approximately $240 monthly. Thus, patients may ask whether a less
expensive brand of strips will work in their machine. Patients even ask
whether older leftover strips will work in a newly purchased machine.
Again, unless the manufacturer specifically approves this practice, the
answer is no.
In an ideal world, manufacturers of blood glucose test
strips would cooperate with each other to market a universal test strip
that would work in any machine, and all future machines would be made
compatible with the universal strip. This would minimize
cost to the patient with diabetes. However, this proposal would
require monumental and unprecedented effort to implement. Unfortunately,
manufacturers work actively to prevent patients from switching strips,
as test strips are a high-profit item. When manufacturers market a new
glucose monitor, they invariably offer a set of strips custom-made for
that machine. This practice locks the patient into purchasing those
newer strips, maximizing company profits.
As a result of manufacturers’ practices, pharmacists must
advise patients to purchase the strips that are specifically made for
their machine. Strips made for older machines must not be used unless
the manufacturer’s website advises that they can be used. Switching
strips from one manufacturer to another is strictly prohibited. Finally,
outdated test strips must be discarded, as the chemical coatings break
down and the strips’ results become inaccurate.5
Patients may ask whether testing in sites other than the fingertips (known as alternate site testing)
is accurate. According to the FDA, meters that claim to allow patients
to take samples from the palm, upper arm, forearm, thigh, or calf can
yield accurate results, but should not be used in certain circumstances.6
For instance, patients should use only their fingertips when blood
glucose levels are changing rapidly, as alternate sites may give
inaccurate results. Other situations when patients should only rely on
fingertip testing include when the patient is ill or under stress, has
just exercised or eaten, has just administered insulin, cannot reliably
detect signs and symptoms of hypoglycemia, believes he or she is
hypoglycemic, and/or if the test results do not agree with the patient’s
perception of his or her blood glucose level.
As to this latter point, patients should be told to rely on their instincts and physical symptoms.5
If the meter yields results that do not seem right, the patient may
have dehydration, high blood osmolarity, a high hematocrit, or incipient
shock. Patients should seek medical assistance if they suspect the
presence of any of these dangerous conditions.
Choosing a Specific Meter
A detailed discussion of meters currently available is
beyond the scope of this article for several reasons. First, at least 80
meters are currently marketed, and they are radically different in the
features they offer.4 Even more important, the blood glucose
meter market is incredibly dynamic. Manufacturers constantly introduce
new versions of their product, each with purported advantages when
compared to other meters. Thus, any article discussing meters is
outdated shortly after it is published. Despite such diversity,
pharmacists can describe various meter options.4
Some meters yield results with sample sizes as small as
0.3 mcL (e.g., FreeStyle Lite, ReliOn Micro), usually suggesting that
smaller sizes allow patients to use alternate sites on the body.4
Other meters have an especially large memory, such as the OneTouch
Ultra Smart (3,000+ results), Contour USB (2,000 results), and WaveSense
Jazz (1,865 results).4
Meters may be particularly useful for those with limited
hearing or vision. Some have audio capability (e.g., Prodigy Voice,
Embrace), and others have a backlight to enhance readability (e.g.,
AccuChek Aviva Combo, OneTouch UltraSmart, Precision Xtra).4
The cost of meters may be an issue. Meters range from
inexpensive (e.g., $19.99 for a Contour meter) to significantly more
expensive (e.g., $149.99 for the Fora D30e/f meter).4 The
patient may find a meter useful if it reads blood pressure in addition
to blood glucose. This can be found in the Fora D10 meter. Other
patients may benefit from the capability to read ketones, as found in
the Precision Xtra and Nova Max Plus meters.4
Patients should be urged to read and understand the
manufacturer’s booklet section that instructs them on how to ensure that
the meter is functioning properly. Whenever a meter is activated, it
performs an internal electronic check.6 A problem is signaled
by an error code in the display. Patients should be instructed to read
the manual, find the meaning of the meters’ various error codes, and see
whether instructions are included for fixing the meter when a specific
error code appears in the display. Patients should also be urged to call
the manufacturer’s toll-free number for advice and not to trust the
meter’s results until they are sure the meter is reliable once again.
Some meters require the user to purchase brand-specific
control solutions. These solutions should be used whenever the patient
opens a new container of test strips, occasionally as the container is
being used, whenever a meter has been dropped, and whenever unusual
results are observed.6 Patients should purchase new quality
control supplies when their expiration dates have passed. Other meters
have electronic test strips that induce a signal to confirm that the
meter is working as it should.3
As a final quality control method, patients can take their
meter to their next medical appointment. The health care provider can
observe their technique for accuracy and can order a blood glucose
laboratory test to match against the meter’s results to see how closely
the meter reflects actual blood glucose.6
The importance of conducting these quality control methods
cannot be overestimated. One seldom-mentioned reason is that the
expiration date on the manufacturer’s test strip container may not be
valid.5 Some companies overestimate the expiration date, so
that the strips lose accuracy while seeming to be up-to-date. Further,
if the cap of the container is not replaced properly, moisture and
ambient air can enter, altering the strips’ accuracy.
Tips to Increase Accuracy
If the patient’s meter seems to yield inaccurate results, there are several tips that can help rectify the situation.5
Patients must be sure to have sufficient blood for the meter. Some
meters give an error code with insufficient amounts of blood, but others
may not, yielding inaccurate results. The strip must be fully inserted
into the meter. If it is not, the display may read high or low. The
meter must be kept clean, as readings can be affected if the lens is
obstructed by what seems to be only a small amount of dirt, grease, or
If the meter requires users to enter a calibration code,
pay close attention so that the correct code is entered, and also be
sure to enter that code when first using the new container of strips, or
whenever a test is run, as advised by the manufacturer. The meter’s
battery may be the problem. Patients should keep several spare batteries
on hand and switch them out to ensure accurate readings.
The temperature at which the machine is used could be
problematic. Meters that operate reliably at low temperatures include
the Sidekick (down to 34˚F), FreeStyle Freedom Lite (40˚F), and Contour
Next Link (41˚F).7 Meters that operate reliably at high
temperatures include the Precision Xtra (up to 122˚F), ReliOn Ultima
(122˚F), Breeze2 (113˚F), and Contour Next EZ (113˚F).7
Importance of Blood Glucose Testing
At one time, patients monitored their glucose status by
placing test strips or tablets in a urine sample. These products were
unreliable and did not give a good indication of the actual amount of
glucose in the blood. Eventually, blood glucose meters became available,
and these devices rapidly replaced the old urine tests to become the
standard method of glucose testing. In fact, self-monitoring of blood glucose
(SMBG) is used by virtually all patients with diabetes today. When it
is done correctly, the results are so reliable that patients can use
them to adjust their insulin, other medications, diet, and exercise.
Steps in Blood Glucose Testing
The steps patients use in SMBG are fairly simple. Many
meters require you to first insert a test strip into a slot in the
meter. With others, you simply remove a test strip from its container.
Next, you must obtain a blood sample. The most common method is to use
an automatic lancet device with a disposable needle. The blood sample
must be transferred to the test strip; then the strip is inserted into
the meter if this has not already been done. Your blood glucose meter
will read and report your blood glucose levels.
Selecting an SMBG System
Manufacturers offer a wide range of glucose meters. Each
model has specific advantages when compared to others. The American
Diabetes Association provides a useful information handout on the
various meters online at http://forecast.diabetes.org/meters-jan2013.
It is critical to note that buying one brand of meter
locks you into a specific brand of matching test strips. Manufacturers
market strips made for their monitors, and strips made for other devices
simply will not work. Even different meters from the same manufacturer
often require a different set of strips. You may be able to find generic
strips that will work in your meter. Be sure that they specifically
mention your meter on their label.
When you choose a blood glucose monitor, ask whether the
meter also comes with a control solution. This is usually a small bottle
of liquid that you can use to determine whether your meter is working
properly. You will put the solution on the test strip in place of your
You should use a control solution for the following: 1) to
practice the testing process without having to draw a blood sample; 2)
to check your meter once weekly; 3) any time you open a new vial of test
strips; 4) if you suspect the meter and/or strips are faulty; 5) if
your results are repeatedly higher or lower than you expect; 6) if you
have dropped or damaged your meter; or 7) if your strips were exposed to
an adverse environmental event, such as moisture or excessive heat. You
should only use a control solution made for your specific meter, and it
should be at room temperature before and during the test.
Remember, if you have questions, Consult Your Pharmacist.
1. National diabetes fact sheet, 2011. CDC. www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf. Accessed August 21, 2013.
2. Glucose tests: common questions. American Association
for Clinical Chemistry.
Accessed August 21, 2013.
3. Getting up to date on glucose meters. For consumers.
FDA. www.fda.gov/ForConsumers/ConsumerUpdates/ucm049051.htm. Accessed
August 21, 2013.
4. Blood glucose meters: 2013 consumer guide. Diabetes Forecast. January 2013. http://forecast.diabetes.org/files/images/v66n01_p41-47_1.pdf. Accessed August 21, 2013.
5. Useful tips to increase accuracy and reduce errors in
test results from glucose meters. FDA.
Accessed August 21, 2013.
6. Blood glucose monitoring devices. FDA.
Accessed August 21, 2013.
7. Blood glucose meters 2013. Diabetes Forecast. January 2013. http://forecast.diabetes.org/meters-jan2013. Accessed August 21, 2013.
8. Type 2 diabetes. Diastix. www.diastix.com. Accessed August 31, 2013.
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