Does It Make a Difference Where You Put Your FreeStyle Libre Sensor?

Dear Dr. Edelman, I love the FreeStyle Libre, but sometimes when I put on a new sensor, the readings are higher than with the previous sensor, even if I didn’t eat anything. Is that normal? Does it make a difference where you put the sensor?

Dr. Edelman: The location on your arms should not matter that much. Wide swings in glucose when you swap out sensors is not uncommon at all, and a lot of folks going on CGM are surprised about that. All sensors can be inaccurate, but you should double check with your glucose meter (yes…prick your finger) to get a comparison. Remember you need to have very clean fingers before testing and there is a thing called the lag time in that if you are going up or down quickly, your finger stick value will lag behind. If you have a sensor that is way off, like over 20% from the finger stick value consistently, call the company to get a replacement sensor for free. Lastly, all sensors are less accurate the first 24 hours after putting on a new one.

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    In “Does it make a difference …” article.., Did he mean to say finger stick would lag or sensor glucose Would lag?

    • Hello…the sensor reading lags since it is not measuring blood like a finger stick does. Interstitial fluid is what sensors measure.

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    3 of the last sensors fell off before 2 weeks? Is there a way to make them stay longer?

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    I believe I have a helpful hint to help with the sensors being not accurate during the first day. During your last full day of your old sensor, keep it on but also attach a new sensor. The next day, remove your old sensor after it has expired and start the new one after putting the transmitter into the new one (if applicable). Since the new sensor has been on for a full day and the tissue has had time to recover from the insertion process, your new sensor should have accuracy right from the beginning.

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    I put a new sensor on and it did the first part and said to wait a hour. When I went to take the first reading it said to replace the sensor. That it wasent working. Now im out a sensor. I haven’t taken it off yet. Was going to wait to talk to the pharmacist on monday.

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