Let’s Talk Libre: New Apps, Alerts, and Add-a-Friend!

By now most of you have heard about Continuous Glucose Monitors (CGMs) that allow you to monitor your sugar without fingersticks.  It’s true!  There are several systems currently available in the U.S. marketplace.  What they all have in common is that you wear a disposable sensor on your body and the glucose readings are transmitted wirelessly to a receiver.  The sensor is a thin filament that is inserted just under the skin.  The receiver is a separate device that is roughly the size of a standard glucose meter or your own smart phone.


Today, I am going to tell you about the FreeStyle Libre 14 day system.  This CGM works for 14 days after a 1 hour warm up period.   The sensor is inserted into the back of the upper arm.  It is waterproof  (for up to 30 minutes, up to 3 feet deep) and discreet.  After the warm up period, the sensor measures the glucose in your tissue fluid every minute!  You see these readings only after holding a reader (the receiver or an iPhone) over the sensor for 1 second.

There is even an App to use your iPhone to look at your CGM readings.  The FreeStyle LibreLink app is compatible only with iPhone 7 and later (running iOS 11 and later).  (Sorry Android users!)  In addition to you being able to see the readings on your phone, you can also designate up to 20 others who can also access your glucose data via their iPhones.  Remember, none of the data is available for review in the App until you actively scan over your sensor with your phone.


Fingersticks are not generally needed after the warm up period.  The FreeStyle sensor is factory calibrated and needs no additional calibrations while being worn.  Fingersticks are still required for treatment decisions if there is a “check blood glucose” symbol displayed on the reader, when you are having symptoms that do not match the CGM readings, when you think the system might be giving an inaccurate reading, or if you are having symptoms that might be due to a high or low blood sugar.  The reader has a built in blood glucose meter, so you don’t need a separate meter.  This meter uses only the FreeStyle Precision Neo test strips.  If those strips are not covered under your health insurance, you can use any meter your insurance covers.


If you have high blood levels of ascorbic acid (Vitamin C) or salicylic acid (aspirin) in your body, these can interfere with sensor glucose readings, but acetaminophen (Tylenol) won’t interfere.  If your blood sugar is under 40, “LO” is displayed on the reader.  If your blood sugar is over 500, “HI” is displayed.  The FreeStyle also tends to overcall hypoglycemia.  In a study, 40% of the time that the Freestyle indicated the glucose was under 60 mg/dL, it was actually 81 mg/dL or higher.  This means that you would need to look at your glucose trend, assess your symptoms, and perhaps do a fingerstick blood glucose reading if the FreeStyle shows that your glucose is low.

Your CGM sensor glucose readings may not exactly match your fingerstick blood glucose readings if tested at the same time.  In part, this is due to the glucose being measured in blood versus in tissue fluid (called “interstitial fluid” or ISF).  The glucose has to move from your bloodstream into your tissues and this takes several minutes.  If your blood glucose level is changing quickly, the change is not reflected in the ISF for several minutes.  Also, even though the system checks your glucose reading every minute, it stores the data for later retrieval only every 15 minutes.  This means the glucose shown on the reader when you scan is the current one (within the last minute), but the tracing of your glucose readings over time reflects 15 minute intervals.

Here are some people who should not use the FreeStyle Libre:  kids under age 18, pregnant women, people on dialysis, or critically ill persons.  Also, this system is not able to proactively alert you if your glucose level is too low or too high.  You have to scan with the reader or your iPhone App to see what your glucose is doing.  For people who are unable to feel a low blood glucose level, a different CGM that can alert you with alarms may be a better choice.  For everyone else, this is a good CGM to consider getting.


The next generation of the FreeStyle Libre, the FreeStyle Libre 2, will offer customizable alarms for low glucose and high glucose, as well as an alert if the sensor is not communicating with the reader.  In any of these events you will be notified through sound or vibration, but you will still need to scan your sensor (or check your blood sugar with a meter) to get a reading. The FreeStyle Libre 2 has been approved in Europe and should be available in the U.S. very soon.


If you want to get a FreeStyle Libre 14 day system of your own, you will need prescriptions from your healthcare provider for both the reader (only 1 needed every year) and the sensors (2 per 28 days).  Most commercial insurance plans will cover this for you.  Medicare provides coverage if several criteria are met and documented in your doctor’s office note:    you have diabetes and have already been testing with a regular blood glucose meter 4 or more times daily and are taking 3 or more daily injections of insulin or are using a Medicare-covered insulin pump and your insulin dose needs “frequent” adjustments.  You will need to see the treating healthcare provider at least every 6 months to continue to qualify.

Using a CGM can be an eye-opening experience into your glucose control that gives you minute by minute feedback on how your actions affect your glucose readings.  You don’t know what you don’t know, but, with a CGM, you will know exactly what your glucose levels are doing.

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    I love this machine. The change in my life. However, the growing pain with it is the following: 1) sensor-1 out of 3 or. 4 has to be return to abbot 2) machine does not have long acting insulin only to 50.
    Still loving it.

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      Technology is never perfect – we hear that from a lot of folks. Glad you found a CGM you love, and thanks for sharing!

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    I have just started to use the Libre 14. Previous A1C has been between 7.1 and 7.4; since using the Libre 14 my last A1C was 6.6. Much more aware of readings and adjustments to make with my Insulin.

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    I have never been able to get my A1c below 7.5. After just 3 months on the Libre my A1c was 6.6. This thing is a life saver!

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    I hope that one of the customizable alarm options is NONE. I used a Dex until a new medication drove it berserk and it wouldn’t measure anything… I’ve been using Libre ever since it became available and love it, even though it does have to have tape added around it in order to make it stay attached for 14 days. Even then, there’s always the possibility of an attack by an aggressive doorway, tight sleeve or bra strap.

    I’ll have to check out the app. One of my daughters likes to keep track of me, so maybe she’ll be interested. The other one, with 8 kids, is way too busy to worry about mom!

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    I have been using the Libre for three months now and I love it. I purchased it to monitor my lows without having to stick myself when I felt horrible. Awesome!

  6. I am disappointed with the system. Started having problems in February and company sent replacement sensors and sent prepaid box to return failed ones to them. Then, realized the reader was at fault. Again company replaced sensor and reader this time. Have had current sensor on a week. It popped off in the shower. I’m done! Since my A1C is low and I’m not on insulin, why do I need to test anyway?

    • I’m sorry about your experience with the Libre. That sounds super frustrating! You may be right that if your diabetes is well controlled, you may not need to test frequently. This depends on what medications you are taking (some other meds can cause low blood sugars besides insulin.) I would recommend discussing with your diabetes doctor. Lastly, if you decide to try the Libre again, there are some tricks to helping it stay on longer. You can use skin tac to help the adhesive stick, or try other tapes/covers to make it stay longer such as tegaderm, IV 3000, or grif grips.

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    I’ve used the Libre for about 4 months now and my A1C went from 7.1 to 6.2.
    I owe most of credit for the change to the Libre since I can now see how different foods affect my glucose levels.
    I also had one of my sensors come off after being attached my a car door frame, the company replaced it for me. Then I found some water proof patches to put over the Sensor and have not had any come off again. I found them at Amazon.

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      Hi William,
      We’re glad you found a device that is helping you so much! Thank you for your comment and tip on the waterproof patches! 🙂

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    I’m using the Libre 14 day sensor and really enjoy it. I do have issues with it popping off. The adhesive around the sensor is so minimal I would think making that area larger would help. Like others, it comes off when my bra strap hits it or clothes, or it simply just pops off. The company has been wonderful with replacing when necessary. I’ve invested in adhesives covers to help keep in place. That being said all is worth it as I am more compliant with checking my sugars, I had an A1C of 12, and now it’s 10. I’m working with Dr and Nutrionist. Continually checking provides important data for me to share. Since I dont have to stick my fingers, and just scan I’m scanning in pairs (before and after meals) and logging it.

    I’m looking most forward to the alerts, as my sugars are dropping overnight and I’m so scared it will happen while I’m sleeping and not feel it. That part is scary.

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    The Libre is a life saver and makes diabetes control much more manageable. Will the Libre 2 reader be compatible with the Libre 1 sensor or will I have to use up the old sensors with the old reader?

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      Hi Tamara,
      The Libre 2 has not yet been approved by the FDA, so we won’t know compatibility until after that point.

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    Abbot and God have answered. I’m an adult onset T1D. The Libre14 with its 1 min samples allowed me to to go from a
    ten finger sticks a day struggling 7.2% (sometimes getting close to 8% !) TO 5.7%.!!!

    I’m using the Walmart special Novalin N at $28 / 10ml (3 week supply for me) , with a simple syringe.

    The trick is dosing. The rate of change information is very, very important. The “BOB” method is very simple , keep your eyes on the road. Bolus of Insulin, then check 1hr and 10 minutes.(it’s that predictable, you usually see a notch in the graph!). rinse and repeat😁.

    Yes, the level is part of the information. My goal is to keep the glucose between the goal post of 70 – 150 mg/dl. not trivial. Insulin slow, OJ fast.

    The actual bolus is a function of slope,level, carb intake, liver activity, exercise, low sugar feeling, etc. THINK like an artificial pancreas.

    I’m using the libre APP on used ($78)Nexus 5X (android). It has logging capability for dosing.
    carb, physical activity,etc. It also downloads automatically to my Endocrinologist and diabetic educator.

    Willing to share.

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    I am new to this system and on my second sensor. It’s placed on back of arm as directions state. I find it to be very inaccurate. Tonight for example, the sensor read ( using iPhone app) 69 and dropping but fingerstick read 130. It took 30 minutes for the sensor to catch up to actually blood sugar readings. So the quickly rising or quickly falling rule does not apply. The only time the sensor is accurate is when blood sugars are stable. Very disappointed. End up using glucose meter 10 times per day because I can’t trust the sensor.

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