A Continuous Glucose Monitor (CGM) tracks glucose levels continuously, providing real-time data without frequent fingerstick checks. Instead of measuring glucose directly from blood, CGMs analyze glucose in the interstitial fluid, the fluid surrounding cells just beneath the skin. Accurate placement of the CGM sensor is important for reliable readings and user comfort.
Common Placement Areas
The primary locations approved by the U.S. Food and Drug Administration (FDA) for CGM sensor placement are the abdomen and the back of the upper arm. These areas are favored because they contain sufficient subcutaneous fatty tissue, where the sensor’s filament resides, allowing for accurate interstitial fluid glucose measurement. Limited muscle movement in these regions also contributes to sensor stability and consistent readings.
Specific CGM brands may have distinct approved sites. For instance, the FreeStyle Libre system is primarily approved for placement on the back of the upper arm. Some Dexcom models, like the G7, are recommended for the back of the upper arm for individuals aged two years and older, while the upper buttocks is an additional approved site for children between two and six years old. Medtronic’s Guardian Connect sensors are approved for both the abdomen and the back of the upper arm.
Choosing the Right Spot
Selecting the best spot for a CGM sensor involves individual lifestyle factors and anatomical features. Personal comfort is a significant factor, as the sensor will be worn for days to weeks. Daily activities and clothing choices should also influence the decision to avoid areas prone to dislodgement or discomfort.
Certain areas should be avoided to prevent inaccurate readings or irritation. These include locations with scars, moles, stretch marks, or tattoos, as they can affect sensor adhesion and accuracy. Bony areas or regions with insufficient fatty tissue should also be avoided, as the sensor requires adequate padding. Avoid spots where clothing might rub or create pressure, or areas that might be bumped or laid on during sleep. Place the sensor at least three inches away from any insulin pump infusion sets or injection sites to prevent interference.
Ensuring Successful Sensor Use
Several practical steps contribute to optimal sensor performance. Regular site rotation is important to prevent skin irritation and maintain sensor accuracy. Avoid using the same spot for consecutive applications.
Proper skin preparation before application is important. The chosen area should be clean, dry, and free of hair. Cleaning the skin with soap and water or an alcohol wipe, and allowing it to air dry completely, ensures proper adhesion. Lotions, oils, or excessive sweat can interfere with the adhesive. Following manufacturer’s instructions, including pressing firmly, helps ensure a secure fit, and many CGM systems include overpatches for additional security and to help the sensor remain in place.