How accurate are blood glucose monitors?

I was using my mom's One Touch Ultra to keep track of my glucose levels during my 3 hour oral glucose tolerance test. I was just wondering how accurate they are compared to the blood drawn by the lab. My last reading was a little funny (my 2 hours glucose was 145 and 3 hour was 149) so I tested again. It went from the 149 down to 127 (both done on same finger, left hand index finger) then back up to 137 (this time with right hand index finger). Then about 10 minutes later before I ate, I used the original hand from before but a different finger (left hand middle finger), and got a reading of 93!!! I'm super confused and don't know which to believe, so it's making me question my other reading that I took...

9 Answers

  • Monica
    Lv 5
    10 years ago
    Favorite Answer

    Yes, readings from home glucose meters can vary somewhat. But when the differences are that big I'm wondering if it's your technique that's the problem. There are so many different factors that can affect your result.

    Are you washing your hands before you test? Are you drying them on a towel that's been out all day? Are you touching the bathroom light switch on the way out? Even the smallest bit of sugar on your finger can send your numbers up. What I do with my daughter is I swipe the finger with an alcohol swab right before testing to make sure the spot I'm taking blood from is 100% clean. If you decide to try this, make sure the alcohol has completely dried off the finger before you prick it.

    But then also watch the hand you're taking the strip out of the vial with. Your best bet is to get your finger in the vial and fish the strip out by touching it in the middle and sliding it out. If you don't touch the ends, then you can be sure you didn't contaminate the strip.

    Oh, and make sure you don't touch the strip with wet/damp hands. Moisture can cause an incorrect reading too.

    Then after you prick the finger, wipe off the first little bit of blood that comes out to make sure you have a fresh sample. Sometimes I do this twice. I use a square of toilet paper for this. Then after you're done you can use the square to hold against your finger until it stops bleeding.

    Do you smear the sample when putting it on the strip? You should try to touch the end of the strip to the droplet of blood, and try not to smear it against your finger.

    How do you get the blood flowing? Do you squeeze the tip of your finger? Squeezing the tip of your finger to get the blood out will often give you higher than normal test results. But there are some other techniques you can try. Try lowering the hand towards the ground and put your other hand around your arm and act like you're pushing the blood in your arm down. The same technique works on the finger. I hold my daughter's finger at the base and squeeze gently from there and push up a little. As long as you're not squeezing so hard that it's putting pressure on the tip of the finger this shouldn't effect the result.

    Source(s): My daughter's a T1 diabetic, and I've been taking her blood sugar about 12x per day for over 2 years now.
  • 4 years ago


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  • 3 years ago


    Source(s): The Complete Diabetes Solution -
  • 4 years ago

    I also use the One Touch Ultra 2 glucose monitor now for about 3 years and yes I also get different results within 30 seconds but I think it is normal because the results are only a little less or more! So just keep on with your monitor but I think if your results are very different from each other take the monitor back and replace it with a new one. Good luck and stay healthy!!

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  • Lennie
    Lv 4
    4 years ago

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  • 10 years ago

    Fingerstick-type glucometers are required to be accurate to within +/-20% of lab results for blood glucose levels of 100 mg/dl or higher and +/-20 mg/dl for glucose levels below 100 mg/dl. In practice, they generally seem to be more accurate than that, but no manufacturers will make any specific claims to greater accuracy than is required.

  • Noccie
    Lv 7
    10 years ago

    Lab results are far more accurate. Home glucometers are not accurate enough for diagnosis purposes but are accurate enough for a person with diabetes to monitor his/her blood glucose level for treatment purposes.

  • Anonymous
    10 years ago

    I have to believe home meters can be way off from lab results. I just compared my meter to a lab result and my meter read 52 points higher. I use One Touch Ultra Mini,

  • Bob
    Lv 4
    10 years ago

    What happened was you were given more sugar than any human would consume at one time. Your sugar spiked and your pancreas went crazy with insulin trying to control it. Then the glucose in your blood stream dropped because you body finally caught up with itself.

    Source(s): In the past I've worked with the Diabetes Society of the Santa Clara Valley as their Outreach Chairman for about 3 years. I've had Type 1 Diabetes since 1974.
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