The 10 Worst Mistakes You Make When Checking Your Sugar

David Mendosa | Sep 3rd 2015 May 9th 2017

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When you use a blood glucose meter to check your level, you may sometimes get a screwy result. When that happens, you may be quick to blame your meter. But often the trouble is much closer to home.

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Not washing your hands

Even if your hands don’t look dirty, when you don’t wash them before you test, you can screw up your result. Especially if you have handled fruit before testing, a study shows that your result could be way off.

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Not washing with hot water and soap

When you wash your hands, it’s important to get your hands as hot as you can comfortably stand. The hot water makes it a lot easier to draw enough blood for the test. Researchers recommend that you wash your hands with hot water and soap, dry them, and then check your blood sugar.

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Not getting enough blood

The most common mistake is not getting enough blood on the test strip. After using dozens of different blood glucose meters since a doctor told me 21 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, the result the meter reports will be off.

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Squeezing your finger

When you don’t get your hands hot enough, you have to squeeze your finger a lot to get enough blood. When you do that, you are getting some interstitial fluid rather than blood. A study shows that this “may lead to unreliable readings."

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Using alcohol to clean your fingers

Even though some blood glucose meter manufacturers think that you should clean your fingers with alcohol, this is a bad mistake. The experts say that this will give you a test result that it too low.

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Testing on the pad of your finger

Don’t test on the pad of any of your fingers, because you have more nerve endings there. Testing there is more likely to be painful both while you’re testing and also later when you use that finger for typing or anything else. Find out which sides of which fingers have the best blood flow. For me its the outside of my little fingers. If you test a lot, it’s a good idea to change the test site in a regular sequence.

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Using test strips that are too old

Researchers from the U.S. Centers for Disease Control and Prevention found that old test strips give inaccurate readings, particularly if they 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.

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Testing at the wrong time

If your A1C level is above 8.4, your fasting level contributed the most to having a blood sugar level that is far too high. But testing two hours after the first bite of a meal is when those of us with well-controlled diabetes need to check our blood sugar. This is especially important when you eat more than a few grams of carbohydrate, which is the only thing that will have much effect on your level.

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Not testing enough

Few of us who have diabetes test enough. Some of us blame our health insurance companies for not paying for enough test strips. That’s not too smart because we can now get test strips for very little money. We need to test in pairs, as I wrote here a few years ago. The idea is simply to test before and after eating, before and after exercise, and before and after reducing stress, like with meditation.

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Doing nothing with what you learn from testing

The worst mistake you can make is not learning anything from your test results, as I wrote at “Don’t Waste Your Time and Money on Diabetes Testing.” Use your testing to change what you do. If your level is too high, your doctor can change your prescription. You can also bring it down to normal with exercise. But it’s likely that the most important change you can make is to change what you eat.

NEXT: 7 Delicious Smoothies for Good Blood Sugar