A Continuous Glucose Monitor (CGM) is a wearable device that tracks glucose levels throughout the day and night without requiring frequent fingerstick tests. This technology provides real-time data, allowing individuals to see their glucose levels and how they change over time. Utilizing a CGM can help in making informed decisions about food, activity, and medication, ultimately contributing to better glucose management and improved health outcomes. Proper sensor placement is important for obtaining accurate readings and ensuring user comfort.
Approved Placement Areas
CGM sensors are designed for specific anatomical locations to ensure accuracy. The primary manufacturer-approved sites commonly include the back of the upper arm and the abdomen. For instance, the FreeStyle Libre system is typically approved for placement on the back of the upper arm. Dexcom G6 sensors are approved for placement on the abdomen for adults aged 18 and older, and on the abdomen or upper buttocks for children aged 2-17 years. The Dexcom G7 also supports the back of the upper arm for adults.
Subcutaneous fat offers a stable environment for the sensor and is less prone to significant muscle movement that could affect readings. While these are the commonly recommended sites, consult your device’s manufacturer instructions, as recommendations vary between CGM models.
Choosing Your Ideal Spot
Selecting the most suitable spot within approved areas involves personal factors for comfort and accuracy. Choose a flat area with minimal movement, as excessive motion affects sensor adhesion and readings. Avoiding areas prone to bumping or friction from clothing, such as waistbands or tight sleeves, prevents accidental dislodgement. Individuals should also consider their typical sleeping positions to prevent placing the sensor in a spot that might be compressed, as this can lead to temporary inaccurate readings.
The presence of scar tissue, moles, or tattoos should also be avoided, as these interfere with sensor placement, adhesion, and accuracy. For instance, the extra layer of ink in tattooed skin may reduce sensor firmness, causing it to slip. Ensuring sufficient subcutaneous fat is important, as the sensor measures glucose in the interstitial fluid within this tissue. While CGMs can function in leaner areas, adequate fat helps provide consistent readings and optimizes space if other devices like insulin pumps are used.
Applying Your Sensor Correctly
Proper sensor application begins with skin preparation for secure adhesion and accurate readings. First, wash your hands thoroughly with soap and water. Clean the application site with an alcohol wipe to remove oils or residue, and allow it to air dry completely.
Some soaps and body washes contain oils that can compromise the adhesive, so ensuring the skin is completely dry and free of moisture is important for optimal bonding. If the area has significant hair, it may be beneficial to trim or shave it a day or two prior to application to ensure better contact with the adhesive.
Once skin is prepared, follow manufacturer’s instructions for sensor insertion. This typically involves using an applicator to quickly insert the tiny sensor filament just beneath the skin. After insertion, ensure the adhesive patch is firmly pressed onto the skin, applying gentle, even pressure around the edges for about 30 seconds to secure it.
After application, a warm-up period is necessary before the sensor begins providing glucose readings, which can range from 30 minutes for devices like the Dexcom G7 to 60 minutes for FreeStyle Libre systems. During this time, the sensor is equilibrating with the interstitial fluid to ensure stable and accurate data.
Maintaining Sensor Performance
To ensure your CGM sensor performs reliably throughout its wear time, several practices can help maintain its integrity and your skin health. Regular site rotation is important to prevent skin irritation, scar tissue buildup, and to promote consistent absorption.
Using the same site repeatedly can lead to the formation of hardened tissue or lipohypertrophy, which may affect insulin absorption and sensor accuracy. Developing a systematic rotation schedule, such as alternating between different areas of the approved sites, can help preserve skin health and sensor longevity.
Keeping the adhesive secure is also important for uninterrupted monitoring. Avoiding lotions or creams on or near the sensor site prevents adhesive lifting.
After showering, gently pat the sensor and surrounding skin dry instead of rubbing vigorously. If adhesive lifting occurs, specialized overlay patches or medical tape provide additional security. Products like skin barriers or tackifiers (e.g., Skin Tac or Skin Prep) can be used before application to enhance adhesion, especially for active individuals or in humid conditions.