Many of us rely on blood glucose testing to stay in control of our sugar levels. But meters can be funny things: there may be times when the readings they provide are inaccurate.

Modern meters have made inaccurate readings less common, but it’s important to know that it can happen, and why.

Bear these six factors in mind when you’re testing your blood.

1. Out of date test strips

All test strips have an expiry date. Check the box to find out if your test strips are out of date.

Out of date test strips should never be used. They often provide inaccurate results. Some test strips have to be used within a month of being opened. Check the box to see if this applies to your test strips.

Test strips that aren’t properly looked after can also lead to an inaccurate reading. Strips should be kept at room temperature, in a cool dry place. They should also be kept in their original container, and not exposed to sunlight.

2. Extreme temperatures can affect blood glucose readings

Extreme temperatures do funny things to blood glucose meters. If it’s a very cold day, try to test your blood sugar inside, where it’s a bit warmer. If it’s a very hot day, see if you can test in the shade if possible.

Studies have found that cold meters tend to produce inaccurately low readings, and hot meters inaccurately high readings.

Specific meters should state what their temperature ranges are. The FreeStyle Lite, for instance, has an operating temperature between 4 and 40 degrees and a storage temperature between -20 and 60 degrees.

3. Sugar, or other substances, on your fingers

There’s a reason we’re advised to wash our hands before testing our blood. We’ve all heard stories of people testing with a smudge of sugar on their fingers and getting readings of well over 30, but it doesn’t have to be sugar. Bits of dirt can also mess up your blood glucose readings. Make sure your hands are as clean as possible when you test your blood.

4. Wet fingers

And once you’ve washed your hands, make sure they are completely dry before you test. The mixture of blood and water can dilute the blood sample, thereby causing a dodgy reading or error message.

Before testing you should wash your hands, then dry them thoroughly.

5. Meter not calibrated

Blood glucose meters sometimes lose their accuracy without any obvious signs, so it’s recommended that you calibrate your meter on a regular basis.

To calibrate your meter, you need to perform a control solution test. The solution sometimes comes with your meter. If it doesn’t, get in touch with the manufacturer: they’ll usually be happy to provide control solution for free. To find out exactly how to calibrate your specific meter, consult the instruction manual.

Ideally, you should calibrate your meter every time you open a new pot of test strips, but calibrating every month or so should be fine.

You should also calibrate your meter if you suspect it’s providing inaccurate results.

6. Dirty meter

Time was that a dirty meter would produce an inaccurate reading. Dirt, dust and other contaminants would be enough to throw off the meter’s accuracy.

These days, meter technology is a bit more sophisticated, and contemporary models shouldn’t need regular cleaning. But try not go let it get too dusty or dirty, and clean any spillages just to be on the safe side. Check your meter’s manual to find out how to keep yours clean.


How do you like your meter? Let us know here.

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