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Diabetes Testing

Operator Error in Diabetes Testing

Saying that operator error is the biggest problem that people who have diabetes have when we check our blood sugar sounds like blaming the victim. But I’m convinced that some mistakes we make when using our meters and test strips and lancets is the reason why testing so often gives us wacky blood sugar numbers.

People with diabetes know all about blaming the victim. For years I have argued against the common fallacy that diabetes is a lifestyle disease caused by our weight and sloth. In fact, most of us have diabetes in our genes, as the new science of genetic testing shows.

But sometimes — and not always — the victim herself or himself causes the error. That’s what is going on with some of the inaccurate readings that those of us who have diabetes often get from our blood glucose meters.

For more than 40 years, people who have diabetes have been lucky to be able to check their blood sugar levels at home and when travelling. We can do it whenever we need to do so. We don’t have to go to a doctor’s office or a hospital or a lab. Consequently, we forgot what a sophisticated testing device we have in our hands. Blood glucose meters are one of very few blood testing devices that the U.S. Food and Drug Administration lets untrained people use.

And we are for the most part completely untrained in how to use our meters. Is it then any wonder that we screw up the procedures once in a while?

Maybe the most common mistake we make is when we don’t get enough blood on the test strip. After using dozens of different blood glucose meters since a doctor told me almost 20 years ago that I have diabetes, I know from my own experience that when I don’t get quite enough blood on the test strip that the result the meter reports will be off. Usually, it will say that my level is much higher than when I test again right away with a full drop of blood.

Of course, the newer meters require much less blood than then did even just 20 years ago. Some meters can give us accurate results with a blood sample of just 0.3 microliters. That’s just a speck of blood, but when we use less than that speck, we still run into inaccurate test results.

We can run into problems even before we get enough blood to satisfy the bloodthirst of our particular meter. I can think of two such problems:

1. Have you ever lanced a finger that you didn’t wash just beforehand? If you happen to have some sugar on your finger, the meter could be reporting your dirty finger rather than your clean blood. Since starch turns to glucose in our bodies, I also wonder if having a little flour on our finger might work the same way.

2. Have you ever had to squeeze your finger a whole lot in order to get enough blood? If so, you might be getting interstitial fluid rather than blood. That might give an inaccurate reading. The way to prevent this is not only to wash your hands but to be sure to warm up our hands and the blood in them by using water that is about as hot as you can stand.

Test strip age is another big factor that can skew our blood sugar results. Researchers from the U.S. Centers for Disease Control and Prevention reported in the journal Clinica Chimica Acta how the meters they tested varied a lot. That’s something we have no control over and not a question of operator error.

But the CDC researchers also found that the test strips could also be the source of inaccurate readings. They reported that the age of the test strip could also be the source of variability in our blood sugar tests, particularly when we use test strips that are beyond their expiration date. While some meters will reject expired strips, not all of them will. And none of them will reject strips that are nearing their expiration dates, and that too, the CDC researchers told me, can give us inaccurate test results.

My message is for us not to be so quick to blame the companies that sell us the blood sugar meters we rely on to keep our blood sugar levels in check. We are well advised to consider the beam in our own eye before we behold the mote in the eye of our brother.

This article is based on an earlier version of my article published by HealthCentral.

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  • Gene Baldwin at

    I have type 2 diabetes. My A1C has dropped from 6.5 to 5.4. My physician said there is an upside down curve of mortality with A1C. After 6.5, the mortality rate increases as A1C decreases . Is this correct?

  • jim snell at

    Oh god, here we go again.

    Yes, using fresh strips, cleaning test spoy carefully before each test and fresh clean lance each time are critical.

    No complaint there. In fact if I see a strange reading ( too high) on a reliable finger tip, I check other hand and then do anothe cleaning of fingertips.

    Yes the new meters and small strips are extremely sensitive to contaniments.

    But here we go again using sophistry to baffle BS.

    The blood system is not a contiguous slowly moving fully mixed system but in fact akin to ethernet where organs – pancreas, liver , kidneys , etc can all dump glucose/hormones, gas on the highway and at any point and the expectation is that the heart pumping action will see every thing finally mixed up.

    Under the best of conditions one can get higher and lower readings that can stop ones heart as highly unmixed blood and addititives whiz by and on the next packet see much lower average readings just like in a gas pipeline that different loads are shoved on it and pumped around.

    There is no Token ring stoichemetric mixing/bus loading here as items are stuffed on and off.

    I am tired of the industry’s sophistry trying to shove all excuses back on the user.

    Depening on your age and if you have been exercising recently, one can find readings all over the place on different fingers.

    Good cleanliness and procedure yes, sophistry and excuses – hell no.