Diabetes: Choosing and Using Your Glucose Meter (cont.)
Sometimes manufacturers change their meters and their test strips.
These changes are not always communicated to the third-party strip
manufacturers. This can make third-party strips incompatible with your meter
without your knowledge. Differences can involve the amount, type or
concentration of the chemicals (called "reagents") on the test strip, or the
actual size and shape of the strip itself. Meters are sensitive to these
features of test strips and may not work well or consistently if they are not
correct for a meter. If you are unsure whether or not a certain test strip will
work with you meter, contact the manufacturer of your glucose meter.
Making Sure Your Meter Works Properly
You should perform quality-control checks to make sure that your home glucose
testing is accurate and reliable. Several things can reduce the accuracy of your
meter reading even if it appears to still work. For instance, the meter may have
been dropped or its electrical components may have worn out. Humidity or heat
may damage test strips. It is even possible that your testing technique may have
changed slightly. Quality control checks should be done on a regular basis
according to the meter manufacturer's instructions. There are two kinds of
quality control checks:
Check Using "Test Quality Control Solutions" or "Electronic Controls".
- Test quality control solutions and electronic controls
are both used to check the operation of your meter. Test quality control
solutions check the accuracy of the meter and test strip. They may also give
an indication of how well you use your system. Electronic controls only check
that the meter is working properly.
- Test quality control solutions have known glucose
values. Essentially, when you run a quality control test, you substitute the
test solution for blood. The difference is that you know what the result
- To test your meter with a quality control solution,
follow the instructions that accompany the solution. These will guide you to
place a certain amount of solution on your test strip and run it through your
meter. The meter will give you a reading for the amount of glucose in the
sample. Compare this number to the number listed on the test quality control
solution. If the results of your test match the values given in the quality
control solution labeling, you can be assured the entire system (meter and
test strip) is working properly. If results are not correct, the system may
not be accurate--contact the manufacturer for advice.
- Manufacturers sometimes include quality control
solution with their meter. However, most often you must order it separately
from a manufacturer or pharmacy.
- Some glucose meters also use electronic controls to
make sure the meter is working properly. With this method, you place a
cartridge or a special "control" test strip in the meter and a signal will
appear to indicate if
the meter is working.
Take Your Meter with You to The Health Care Provider's Office. This way you can test your glucose while your
health care provider watches your technique to make sure you are using the meter
correctly. Your healthcare provider will also take a sample of blood and
evaluate it using a routine laboratory method. If values obtained on the glucose meter match the laboratory
method, you and your healthcare provider will see that your meter is working
well and that you are using good technique. If results do not match the
laboratory method results, then results you get from your meter may be
inaccurate and you should discuss the issue with your healthcare provider and
contact the manufacturer if necessary.
User Experiences with Glucose Meters
The FDA's Center for Devices and
Radiological Health (CDRH) held a series of focus groups on blood glucose meter
use in 2001. The twenty-two members participated in six groups. They were all
government employees, mostly from CDRH. They were either people with diabetes or
family members of people with
diabetes who were familiar with the use of glucose meters.
Most of the participants in these groups were satisfied
with their meters. Some were quite enthusiastic about the new models. A few had
some concerns about meters. One such participant stated: "The first meter I got I couldn't use
because it was too difficult."
Repeating Tests. Most users repeated tests now and then because they
believed the first test result was incorrect. Users questioned test results
based on their expectations about what the results should be. If the glucose
level seemed "off," they repeated the test.
The ability to judge whether or not a test seemed accurate appeared to come
from the users' experiences with their meters. These experiences helped them
know how they felt when their glucose level was high, when it was low and when
it was about right. They also were aware of what and when they had eaten,
exercised, slept, or taken insulin, and they learned to anticipate the effect
these activities have on their glucose levels.
Comments users made about their results include the following:
- I sometimes get a reading of perhaps 300 and then 180
on a retest. This happens in about 1 in 50 tests.
- Glucose tablet residue on my finger can throw results
- I get some inaccurate readings - especially when the
meter is new.
- Sometimes I get higher readings than I expect,
probably because the meter was left out of the case or food got on it.
- The date wears off of the vial and I end up using
- Humidity around the bathroom seems to affect
performance of the strips.
- If I have wet hands, my results tend to be higher than expected.
Besides repeating tests because of a suspected inaccuracy
in the first test, a frequent reason to repeat a test was that the meter indicated "insufficient
blood" on the test strip and would not complete the test on the first attempt.
When this happens, users needed to do another fingerstick. Users whose meters
required less blood did not have this problem as often.