FreeStyle Libre CGM Cleared for Use During Imaging Tests

For users of continuous glucose monitors, getting an MRI or other imaging test typically means removing – and discarding – their CGM. Most manufacturers recommend taking the devices off to avoid damage. Last week, however, Abbott announced its FreeStyle Libre 2 and 3 systems have been cleared by the FDA to stay on during MRI, CT scans, and X-ray procedures. 

"This was a roadblock for patients, who unfortunately needed to dispose of their devices for a simple procedure, adding cost, discomfort, and burden," said Dr. Rodolfo J. Galindo, director of the Comprehensive Diabetes Center for the University of Miami Health System. "This is without a doubt a step forward for people with diabetes."

Also, because CGMs require 20-60 minutes of start-up time before they begin providing readings, this can further delay use of the CGM beyond the time of the procedure. 

Additionally, some insurance policies won't replace a sensor removed for procedures, leaving the user a sensor short from their prescription.

Galindo said patients have sometimes been asked to remove sensors during X-rays and CT scans, even when the CGM sensor was outside of the area being imaged. 

"Scientifically, this did not make too much sense, but patients were bearing that burden of care, cost and inconvenience," he said.

Now there is clear guidance for Freestyle Libre sensors. The recent FDA decision removed the contraindication labeling for the Freestyle Libre 2 and 3 in these imaging procedures. 

Galindo pointed out that CGM users who continue to use them during an MRI may not be able to rely on the readings during the procedure. He also advised that users back up the sensor readings with a glucometer after the procedure to confirm readings are normal.

"Not having to remove the CGM does not remove the need to be careful with glucose and the treatment decisions during the procedure and after," Galindo said. 

Abbott says that CGM readings may be affected during an MRI, but the readings should return to normal within an hour.  

Among other CGM systems, guidance varies. For example, the Eversense 365 has a sensor that's implanted under the skin, and also has a transmitter that can be removed and reapplied without losing the sensor. Eversense advises removing the transmitter during an MRI, CT scan or X-ray. Glucose data returns within 10 minutes of reconnecting the transmitter.

Dexcom's current guidance for its sensors states that they should be removed for MRIs and for CT scans. For X-rays, the sensor should be kept out of the scanned area and covered with a lead apron.

The bottom line

Abbott’s Freestyle Libre 2 and Libre 3 (as well as Libre 2 Plus and Libre 3 Plus) can be worn during imaging tests, reducing the burden of removing the CGM devices for these procedures.

Libre CGM readings may not be accurate during MRI scans. The company says "uncompromised" readings will return after 1 hour. This guidance also applies to the Plus version of the Libre sensors used in automated insulin delivery systems.

Check the manufacturer's website for your CGM to find out if you can wear it during certain imaging procedures. Guidance varies by manufacturer.

 See news and tips on CGM use:

• More Choices Available for Abbott, Dexcom, Tandem, and iLet
• 7 Common CGM Hang-Ups (and How To Get Around Them)
• 42 Factors That Affect Blood Glucose