A continuous glucose monitor (CGM) sensor failure can be a frustrating and disruptive experience. This is a common hardware or software issue that requires immediate attention to restore your glucose monitoring capabilities. The problem is typically confined to the sensor itself, and a replacement can quickly get you back on track. This guide offers a step-by-step procedure for safely resolving the issue and preventing future failures.
Interpreting the Sensor Failure Message
A definitive “Sensor Failed” alert from your device or app means the sensor is no longer capable of measuring glucose and cannot be saved or restarted. This message is distinct from a temporary “Signal Loss” or “Sensor Error” that might resolve itself within a few hours. The system has determined the sensor is completely unusable.
The underlying reasons for an immediate failure are typically related to the insertion process or internal components. Striking a small blood vessel and causing bleeding at the site can disrupt the sensor’s ability to read interstitial fluid glucose concentrations. Communication failures are also common, often due to the transmitter not being properly seated or an incorrect serial number being entered during setup. Internal filament damage or a manufacturing defect can also cause the sensor to fail the initial warm-up calibration.
Step-by-Step Safe Removal
Once you receive the permanent failure notification, the old sensor must be removed immediately. Before peeling it off, consider using a medical adhesive remover wipe or spray around the edges of the patch. This helps dissolve the strong medical-grade adhesive, minimizing skin trauma and discomfort.
Peel the adhesive back slowly and gently, pulling it parallel to the skin rather than lifting it straight up. Pulling at a low angle helps to separate the adhesive bond without painfully tugging at the epidermis. After the sensor is off, inspect the insertion site for any signs of irritation, excessive bleeding, or remaining sensor components. If there is any bleeding, press lightly with a clean gauze pad until it stops. Carefully dispose of the failed sensor, as manufacturers may request the return of the unit for quality control testing.
Proper Application of the New Sensor
Selecting a new insertion site is the first and most important step to ensure the replacement sensor works correctly. Always rotate the site, choosing a location that is approved by the manufacturer and is physically distinct from the previous one to allow the skin to heal. Avoid areas with scars, heavy hair growth, or where the sensor is likely to be bumped or pressed against.
Meticulous skin preparation is necessary to ensure the adhesive bond lasts for the full wear period. Clean the chosen area thoroughly with an alcohol wipe to remove all surface oils and dirt. Allow the skin to air-dry completely for at least 30 seconds before proceeding, as residual moisture can significantly compromise the adhesive’s grip.
Use the applicator to insert the new sensor according to the manufacturer’s instructions. After insertion, press firmly around the adhesive patch for up to a minute to secure it to the skin. This pressure helps ensure full contact with the skin’s surface. Only after the sensor is securely in place should you initiate the warm-up process.
The warm-up period is mandatory, typically lasting between one and two hours. During this time, the sensor is stabilizing and calibrating itself. Avoid touching, bumping, or applying pressure to the sensor during this window to prevent a recurrence of the failure error.
Addressing Data Gaps and Future Prevention
The period between removing the failed sensor and receiving readings from the new sensor creates a temporary data gap. During this warm-up time, you must rely on a traditional fingerstick blood glucose meter to make any treatment decisions. This is the only way to accurately monitor your glucose levels until the new CGM is fully operational.
To minimize the chance of future failures, focus on improving your site selection and skin hygiene. Always use an approved insertion site and check that your skin is completely free of lotions, oils, or soap residue before application. If you regularly experience adhesive failure, consider using an adhesive barrier wipe or a medical overlay patch to provide extra security, especially if you lead an active lifestyle or sweat frequently.
Remember that sensor failures are sometimes due to manufacturing defects that are beyond your control. If a sensor fails prematurely, contact the manufacturer’s technical support line immediately, as they will typically replace the faulty unit free of charge. Keeping the sensor’s packaging and serial number handy will streamline this replacement process.