A continuous glucose monitor (CGM) is a small, wearable medical device that tracks glucose levels beneath the skin, offering real-time data. The core components include a sensor, a transmitter, and a receiver or smartphone app. The primary question for many users is whether this technology can withstand water exposure. Modern CGMs are designed to accommodate normal water activities like swimming and showering, provided certain precautions are followed.
How Manufacturers Rate Water Resistance
Manufacturers define a sensor’s ability to resist water intrusion using the Ingress Protection (IP) rating system, a standardized measure for electronic devices. This rating consists of “IP” followed by two numbers, the second indicating water resistance. A common rating for CGMs is IPX7, meaning the device can withstand temporary immersion up to 1 meter (about 3 feet) for 30 minutes. Some advanced sensors carry an IPX8 rating, indicating they can handle continuous submersion deeper than one meter, with specific depth and time limits set by the manufacturer. These ratings apply only to the sensor and transmitter, not the separate receiver or display device, which must be kept dry.
Recommended Swimming and Water Activity Practices
The sensor hardware is protected by its IP rating, but the adhesive that keeps it attached is the most vulnerable part during water exposure. Prolonged exposure, even within rated limits, can weaken the bond, making it advisable to limit swim duration. Vigorous water activities involving high-impact force, such as diving or wakeboarding, increase stress on the device and adhesive, risking dislodgement or malfunction.
The type of water also affects adhesion longevity. Chlorine in pool water and saltwater can accelerate the breakdown of the adhesive bond. Exposing the sensor to extreme temperatures, such as those in saunas or hot tubs, can affect glucose readings and damage the adhesive. Most CGMs operate best between 10°C and 45°C (50°F to 113°F); temperatures outside this range may cause temporary sensor errors.
Post-Water Care
After leaving the water, treat the sensor site gently to preserve the remaining adhesive. Users should pat the sensor and surrounding skin dry instead of rubbing vigorously with a towel. This minimizes friction that could cause the edges of the patch to lift prematurely.
Keeping Your Sensor Securely Attached
The physical loss of the sensor due to adhesive failure is the primary concern during water activities, which can be mitigated through proper preparation and reinforcement. Before applying a new sensor, the skin must be clean and free of oils, lotions, or sunscreen, as these residues reduce adhesive strength. Cleansing the application site with an alcohol wipe and allowing it to fully dry maximizes the bond.
Reinforcement Techniques
To provide additional security, many users rely on accessory products. This includes using a skin-toughening barrier wipe before application, followed by adding a waterproof external adhesive patch, or overpatch, on top of the sensor. Overpatches, often made of stretchable fabric, distribute the forces of friction and water exposure, significantly improving retention during extended activity. Allowing the adhesive, barrier wipe, and overpatch to fully cure for at least an hour before entering the water establishes a stronger, more durable hold.
What To Do If The Sensor Fails After Water Exposure
If a sensor is compromised by water, signs include inconsistent or inaccurate readings, “sensor error” messages, or loss of signal. A sudden malfunction after swimming suggests water intrusion or adhesive failure. Users must immediately confirm the CGM reading with a traditional fingerstick blood glucose meter to ensure safety.
If the sensor is visibly detaching or readings are unreliable, it should be removed and replaced. Contact the device manufacturer’s technical support line, providing the sensor’s serial number and a detailed description of the water exposure event. Manufacturers often replace failed sensors at no cost if they determine the malfunction was a product issue rather than user error.