FreeStyle Libre Troubleshooting: Aches and Errors

Some of the most common questions we have in our Diabetes Daily forum — a vital community of thoughtful, experienced people with diabetes! — concern the FreeStyle Libre, the popular continuous glucose monitor (CGM) made by Abbott. The Freestyle models are often less expensive than the competing Dexcom models, and in some parts of the world they’re much easier to access. The Libre 3, which is now available in the United States and many other parts of the world, is the best yet. Read our rave review here.

The FreeStyle Libre CGMs are great at what they do, but a few issues keep popping up, so we thought we’d write a troubleshooting guide.

My FreeStyle Libre Shows Low/High Blood Sugar. My Fingerstick Doesn’t.

Some of our community members have complained that their FreeStyle Libre seems less accurate, especialy when it comes to high or low glucose numbers.

The FreeStyle Libre 2 and 3, just like the Dexcom G6, are FDA-approved to be used without fingerstick calibration — that is, the system meets the accuracy standards set by federal regulators.

With that said, plenty of users are at least a little bit skeptical about their CGMs, and when in doubt tend to trust their traditional glucose meters. A CGM samples interstitial fluid (not blood), which actually shows what your blood glucose level was about 10 minutes ago. The evidence suggests that the best glucose monitors are, in fact, more accurate than a CGM system: How Accurate are Blood Sugar Meters and Continuous Glucose Monitors, Really?

In reality, experienced users often consider multiple pieces of evidence when deciding how to treat low or high blood sugar: not just the CGM and glucose meter results, but also their symptoms and their understanding of the last few hours of blood sugar decision making, e.g., “Did I just exercise?” or “Did I forget to snack?” Our advice is that you don’t have to rely on the Libre entirely. Use it as one of multiple ways to make glucose management decisions.

My FreeStyle Libre is Always Inaccurate at First

Many users find that the Libre is inaccurate for the first 12-48 hours. That’s because it is less accurate. The manufacturer’s own study numbers show that the sensor takes a day or two to really get into the groove.

If that’s the case for you, our advice is “don’t sweat it.” Just take those first readings with a grain of salt (see above) and wait for your sensor to hopefully hit its stride.

If your sensor remains inaccurate after a few days, it might be time to call Abbott and let them know. They may decide to replace your sensor for you.

My Sensors Keep Failing

Unfortunately, some users experience a high rate of sensor failure. Sensors that are supposed to last 14 days may not make it that long, one way or the other.

The solution? Make a note of the issue, write down any error codes, and then call Abbott and explain your problem. They are usually happy to send you a new sensor to replace the one that didn’t work out, and most of our forum members have been pleased with the level of customer service.

Error – Try Again in X Hours

Some users repeatedly get these frustrating error codes when they swipe their smartphone over their FreeStyle sensor. If it does finally work, sometimes the Libre has no glucose data for the previous 8 hours.

There’s no fix to this problem, to our knowledge. Just stick with it, and trust your traditional glucose meter in the meantime. If the sensor never comes back to life, call Abbott and request a replacement. They’re usually happy to do so.

Do I Have to Wear it on My Arm?

You’re supposed to wear it on the back of the arm — that’s the only location the Libre is approved for. However, as with the Dexcom, users have found other locations that they like just as much, with little or no apparent loss of accuracy.

Other spots that might work for your Libre, if you prefer, include the thighs, the belly or lovehandles, the hip, the upper butt, or upper chest.

While these alternative sites seem to work just fine, it may pay to be cautious. A 2018 study of the Libre suggested that the upper thigh performs just as well as the upper arm, but that the abdomen “performed unacceptably poorly.”

My Sensor Hurts My Arm

Most people find the FreeStyle Libre sensor is completely painless. But a minority of users do complain about pain from insertion that may not go away during subsequent days. If your sensor leads to persistent pain, we would recommend trying a new site, especially one that is fattier or fleshier. Maybe use less pressure when you insert the sensor. The closer your sensor is to a muscle, the more problems it seems to cause.

My Sensor Keeps Falling Off

Whether it’s sweat, muggy weather, swimming, or bumps into door frames, sensors have an annoying and potentially expensive habit of falling off. CGM users have devised many ways to improve adhesion, including the following:

Wash your skin with soap and water before insertion in order to remove grease and dirt. Shaving may help too.
Prepare your skin with Skin-Tac adhesive wipes, basically a glue that helps the sensor’s adhesive stick better to your skin.
Tape over the sensor with transparent medical tape, such as OpSite FlexFix.
Purchase a specially-made adhesive for your CGM – some of these rugged stickers can be found in cool colors and designs, and are cut to fit a Freestyle Libre perfectly.
Purchase a specially-made armband instead of extra tape.
Experiment with a new placement less likely to receive bumps and bruises.

The Adhesive Irritates My Skin

Some patients experience mild or serious skin irritation in response to the sticky stuff that Abbott uses on the Libre sensor. Symptoms may include rash and itchiness, or worse. CGM manufacturers have been changing their chemicals to try and find mixes that have the least impact on sensitive patients, but those solutions may not help you.

First, try washing your skin before applying the sensor. Skin prep protective wipes, which form a sticky barrier between the tape and your skin, may also be helpful.

You can also experiment with different types of tapes and find one that does not irritate your skin. If you find one, cut out a patch with a hole in the center for the sensor’s wire, attach that to your skin first, and then apply the Libre to the tape. This may be less durable, but most of the Libre’s adhesive material won’t be touching your skin.

There’s an entire Facebook group dedicated to this issue: Dexcom and Libre Rash. That community numbers over 15,000 — undoubtedly someone has had the same exact issue and is ready to help you with your problem.


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