A FreeStyle Libre sensor provides continuous glucose monitoring (CGM) by measuring glucose levels in the interstitial fluid, which is the fluid surrounding cells just beneath the skin. This technology offers a convenient way for individuals with diabetes to track their glucose trends without frequent finger pricks. Understanding the expected lifespan of these sensors is important for consistent and effective diabetes management, allowing users to plan replacements and maintain continuous insights into their glucose levels.
Standard Sensor Lifespan
FreeStyle Libre sensors are designed for a specific wear period, determined by the manufacturer to ensure accuracy and user comfort. Both FreeStyle Libre 2 and 3 sensors are approved for 14 days of continuous wear. The FreeStyle Libre 2 Plus and 3 Plus models offer an extended wear time of up to 15 days. This duration allows for consistent monitoring, providing a comprehensive glucose picture over two weeks.
The sensor automatically deactivates once it reaches its predetermined lifespan, ensuring data remains accurate. This fixed wear time helps minimize the risk of decreased accuracy or skin irritation from prolonged use. After application, the sensor requires a 60-minute warm-up period before providing glucose readings, allowing the sensor and body to synchronize. The FreeStyle Libre 2 sensor measures glucose every minute and stores readings every 15 minutes, while the FreeStyle Libre 3 streams data every minute to the app.
Recognizing When a Sensor Needs Replacement
While FreeStyle Libre sensors are designed to last their full duration, certain signs may indicate a need for earlier replacement. Inconsistent or inaccurate readings that do not align with how an individual feels or with readings from a blood glucose meter are a common issue. A significant discrepancy, such as readings being off by more than 20% compared to a fingerstick, suggests a potential problem. Error messages displayed on the reader or smartphone app, or a complete absence of readings after scanning, also signal sensor malfunction.
Physical issues can also necessitate early replacement. If the sensor feels loose, begins to peel, or detaches completely before its wear period is over, it will no longer provide reliable data. Skin reactions at the application site, such as discomfort, redness, significant irritation, or itching, are also reasons to remove and replace the sensor. Continued reliance on a faulty sensor can lead to incorrect diabetes management decisions, highlighting the importance of addressing these issues promptly.
Maximizing Sensor Adhesion and Accuracy
To help a FreeStyle Libre sensor last its intended duration and provide optimal performance, proper application and care are important. Selecting a flat area on the back of the upper arm that remains undisturbed during daily activities is recommended for application. Before applying, the skin should be clean, dry, and free of lotions or oily residues. Using a non-moisturizing, fragrance-free soap and an alcohol wipe, then allowing the skin to air dry, can help ensure good adhesion. Rotating sensor sites between applications helps prevent skin irritation.
Protecting the sensor from physical impact is also beneficial. Users should be mindful of bumping or catching the sensor on objects like doorways or seatbelts. Wearing loose-fitting clothing can reduce friction and pressure on the sensor. If additional security is needed, medical-grade adhesive overlays can be used, ensuring the sensor’s central opening is not covered.
Staying adequately hydrated can indirectly support sensor function by maintaining interstitial fluid concentration. Unopened sensors should be stored within a temperature range of 4°C to 25°C (39°F to 77°F) to preserve their integrity.