FACTORS THAT AFFECT GLUCOSE METER

Performance And Making Sure Your Meter Works Properly

The accuracy of your test results depends partly on the quality of

your

meter and test strips and your training. Other factors can also make a

difference in the accuracy of your results.

Hematocrit.

Hematocrit is the amount of red blood cells in the blood. Patients

with

higher hematocrit values will usually test lower for blood glucose

than

patients with normal hematocrit. Patients with lower hematocrit values

will test higher. If you know that you have abnormal hematocrit values

you should discuss its possible effect on glucose testing (and HbA1C

testing) with your health care provider. Anemia and Sickle Cell Anemia

are two conditions that affect hematocrit values.

Other Substances.

Many other substances may interfere with your testing process. These

include uric acid (a natural substance in the body that can be more

concentrated in some people with diabetes), glutathione (an

"anti-oxidant" also called "GSH"), and ascorbic acid (vitamin C). You

should check the package insert for each meter to find what substances

might affect its testing accuracy, and discuss your concerns with your

health care provider.

Altitude, Temperature and Humidity.

Altitude, room temperature, and humidity can cause unpredictable

effects

on glucose results. Check the meter and test strip package insert for

information on these issues. Store and handle the meter and test

strips

according to the instructions.

Third-Party Test Strips.

Third-party or "generic glucose reagent strips" are test strips

developed as a less expensive option than the strips that the

manufacturer intended the meter to be used with. They are typically

developed by copying the original strips. Although these strips may

work

on the meter listed on the package, they could look like strips used

for

other meters. Be sure the test strip you use is compatible with your

glucose meter.

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 should be.

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.

Source: FDA Thanks Jerry