A Continuous Glucose Monitor (CGM) is a small, wearable medical device that measures glucose levels in the interstitial fluid just beneath the skin. This technology provides real-time data, trend information, and alerts to aid in diabetes management. When facing a medical procedure like an X-ray, which uses a small dose of ionizing radiation to create internal images, patients frequently question the safety of keeping their device in place. Understanding the specific guidance for your technology is paramount before any imaging procedure.
Manufacturer Recommendations for Standard X-rays
The guidance on wearing a CGM during a standard planar X-ray is not uniform across all devices and requires consulting the specific product’s instructions for use. For instance, recent generations of the FreeStyle Libre system, including the Libre 2 and Libre 3, have been cleared by the FDA to be worn during X-ray imaging without the need for removal. This makes them the first and only patient-applied sensors approved for this type of screening. In contrast, other major manufacturers, like those producing the Dexcom G6, generally advise users to remove their device before an X-ray or CT scan. This caution is a preventative measure because the device has not been tested against every possible X-ray machine or radiation dose to guarantee proper function afterward. Despite this official caution, studies simulating high-dose X-ray exposure have indicated that the wearable components retain their basic functionality.
How X-rays Interact with CGM Components
The primary concern regarding X-ray interaction is the possibility of damage to the small electronic components within the transmitter and sensor housing. Continuous glucose monitors contain micro-batteries, sensor wires, and circuit boards that could theoretically be affected by ionizing radiation. However, the dose delivered during a routine diagnostic X-ray is significantly low, making the actual risk of component failure minimal.
A more practical issue is the physical presence of the device potentially obscuring the X-ray image. Devices contain materials like certain metals and dense plastics that absorb X-rays differently than soft body tissues. This differential absorption can create a dense shadow, known as an artifact, on the final image, which could hide the area the medical team is trying to view. If the CGM is located directly in the path of the X-ray beam for the body part being examined, its removal is often requested to ensure a clear and accurate diagnostic image.
Distinguishing X-ray Safety from Other Imaging Scans
It is important to distinguish standard X-rays from other diagnostic procedures, as the underlying technology and safety risks differ significantly. Computed Tomography (CT) scans use X-ray technology but take numerous images from multiple angles to create cross-sectional, three-dimensional views. Because CT scans involve a higher cumulative dose of ionizing radiation and a greater chance of creating image artifacts, the risk to the device and the image quality is generally higher than with a single planar X-ray.
Magnetic Resonance Imaging (MRI), however, presents the most substantial difference and risk, as it uses powerful magnetic fields and radiofrequency (RF) energy, not ionizing radiation. All CGMs containing metal components are universally contraindicated for MRI because the strong magnetic field can cause the metal parts to heat up rapidly, potentially resulting in skin burns at the insertion site. The magnetic forces can also pull on the device or permanently corrupt the sensor’s electronic data and calibration.
Handling CGM Removal and Reapplication
If you are using a CGM that is not cleared for X-rays or if the device is positioned to interfere with the image, a removal plan must be discussed with your healthcare provider. You should always inform the imaging technician about your device before the procedure begins.
Safe removal involves peeling off the adhesive patch, ensuring the sensor wire has been completely withdrawn, and disposing of the used sensor and transmitter according to the manufacturer’s instructions.
During the period the CGM is off, you must temporarily rely on traditional fingerstick blood glucose monitoring to make treatment decisions and track your levels. Once the X-ray is complete, a new sensor must be inserted at a clean, new site, following the device’s application instructions. All CGMs require a warm-up period, typically between one to two hours, before they begin providing accurate readings, creating a temporary gap in continuous data.