The FreeStyle Libre 2, Libre 2 Plus, Libre 3, and Libre 3 Plus sensors are rated “MR Conditional,” meaning they can safely stay on your body during an MRI under specific conditions. However, the original FreeStyle Libre and Libre Pro systems carry a different designation: Abbott’s labeling requires removal before any MRI scan. Which model you wear determines what happens next.
What “MR Conditional” Actually Means
Medical devices get one of three MRI safety labels: MR Safe, MR Conditional, or MR Unsafe. “MR Conditional” means the device has been tested and poses no known hazard in an MRI environment, but only when used within defined parameters. For the Libre 2 and Libre 3 sensor families, those parameters include both 1.5 T and 3 T scanners, which covers the vast majority of clinical MRI machines in use today.
The older FreeStyle Libre Pro system, by contrast, lists MRI as a contraindication. Abbott’s FDA-cleared labeling states the system “must be removed prior to Magnetic Resonance Imaging” because the effect of MRI on its performance “has not been evaluated” and “exposure may damage the Sensor.”
Physical Risks During a Scan
The main concern with any wearable sensor in an MRI is heat. MRI scanners use powerful radiofrequency pulses to generate images, and those pulses can heat conductive materials sitting on your skin. Thermal injuries account for 59% of MRI adverse effects reported to the FDA, and they typically happen when RF energy interacts with metal or electronics touching the body.
Testing on newer continuous glucose monitors (including the Libre family) found reassuring numbers. At standard clinical power levels, the maximum temperature rise was 2.1°C in a 1.5 T scanner and 2.5°C in a 3 T scanner. Both are well below the safety threshold of 6.0°C. Gradient-induced heating added less than 1°C. In practical terms, you’re unlikely to feel any warmth at the sensor site during a scan with a conditionally approved model.
There’s also no meaningful risk of the sensor being pulled off your arm. The magnetic force required to dislodge a sensor (over 328 T/m) far exceeds anything a clinical MRI produces.
What Happens to Your Glucose Readings
Even with the newer sensors that are safe to wear, your glucose data will be unreliable while the scanner is running. Laboratory testing found that during MRI exposure, sensors produced readings that deviated by more than 10 mg/dL from their true values, and all tested models displayed numbers outside their normal operating limits. The radiofrequency energy interferes with the tiny electrical currents the sensor uses to measure glucose.
The good news: this effect is temporary. All sensors returned to accurate readings within one hour after the scan ended. The device itself isn’t permanently damaged. So if you leave your Libre 2 or Libre 3 on during an MRI, plan to ignore the readings for about an hour afterward and use a fingerstick meter if you need to check your blood sugar in that window.
How to Prepare for Your MRI
Start by confirming which sensor model you’re wearing. If it’s a Libre 2, Libre 2 Plus, Libre 3, or Libre 3 Plus, you can keep it on. If it’s an older model, you’ll need to remove it before entering the scan room, which means you’ll also need a new sensor afterward.
Regardless of your model, a few steps make the process smoother:
- Bring a fingerstick glucose meter. You’ll want a backup way to check your blood sugar, since your sensor readings won’t be reliable during and shortly after the scan.
- Check your glucose before the scan. Confirm your blood sugar is in a comfortable range before the procedure begins, especially if the scan could last 30 minutes or longer.
- Bring backup insulin supplies. If you use insulin, pack a syringe or pen in case of any device issues.
- Tell the radiology technologist. Let them know you’re wearing a glucose sensor. They can note it and watch for any unusual alerts during the scan.
The FDA recommends contacting the doctor who manages your diabetes before the scan to make a plan for that day, particularly if you’re also wearing an insulin pump (which has its own, separate MRI restrictions).
CT Scans and Other Imaging
MRI isn’t the only scan that raises questions. Abbott’s older labeling also lists CT scans and diathermy (a type of deep-heat therapy) as contraindications for the Libre Pro. The FDA’s broader guidance for all wearable diabetes devices recommends removing them before diagnostic X-ray imaging or radiation therapy when it’s safe and practical to do so. If removal isn’t possible, the technologist can take steps to minimize direct radiation exposure to the sensor’s electronics, such as using the lowest effective dose or repositioning the device away from the imaging field.
For high-energy radiation therapy (10 MV or greater), the FDA is more direct: the device should not be worn during the procedure regardless of model.