<https://www.reddit.com/r/Freestylelibre/comments/1cma669/bodybuilder_where_to_place_the_fsl/l2zjn9h/>

**General Advice for Sensor Placement**

- Choose a skin area that remains relatively flat during daily activities and muscle exertion. Avoid areas prone to bending, folding, or extreme stretching.
- **Important for Strength Training:** Never place a sensor directly on top of major muscles.
**Recommended Location: Back of Upper Arm**
- The **back of the upper arm** is the officially recommended location for most blood glucose sensors, including the Freestyle Libre 3.
- **Specific Placement:** Position the sensor on the fatty area at the back of the upper arm, between the tricep and deltoid muscle bundles. Avoid placing it directly over muscle.
- **Why it works:** When applied correctly on the upper arm the sensor is stable and less likely to detach.
- The area has minimal bending
- There is sufficient subcutaneous fat

**Site Preparation**

Proper site preparation is crucial for sensor adhesion and accuracy. Follow these steps:
1. **Cleanse:** Wash the area with a neutral, unscented soap. Avoid soaps containing moisturizers or hydrogenated oils.
2. **Shave:** Carefully shave the area with a razor to remove even fine, barely visible hairs.
3. **Disinfect:** Wipe the area thoroughly with an alcohol swab.
4. **Dry:** Allow the skin to air dry completely.
5. **Apply:** Place the sensor on the dry skin and apply firm, even pressure with the applicator. Make slight circular motions to ensure the sensor is well-adhered to your skin around its edges.

<https://www.reddit.com/r/Freestylelibre/comments/1gjhi9e/how_to_apply_a_new_sensor_best_practice/>

**Best Practices for Applying and Starting a New Libre Sensor**

Some users experience issues with sensors detaching, providing unreliable readings, or displaying error messages after startup. These best practices, gathered from experienced users, can help mitigate these problems.

**Application Steps:**

1. **Cleanse:** Shower or wash the intended sensor location with a neutral, **oil-free** soap. Do not use any skin moisturizers on this area.
2. **Shave:** Shave the entire area, even if hair is not readily visible. Skin hairs can interfere with adhesion and trap moisture, leading to detachment.
3. **Dry:** Ensure the skin is completely dry after washing.
4. **Disinfect:** Clean the area thoroughly with an alcohol swab to remove skin oils.
5. **Air Dry:** Allow the alcohol to evaporate completely and the skin to dry fully before proceeding.
6. **Apply:**
- Apply the sensor using the applicator.
- Press firmly down on the applicator top for 20-30 seconds.
- Wiggle the applicator slightly to ensure the sensor's edge adheres completely.
- **Caution:** Prolonged, excessive pressure may prevent the sensor filament from properly anchoring at the intended 6mm depth, potentially leading to inaccurate readings (chronically lower than finger-stick tests).
7. **Remove Applicator:** Gently lift the applicator off.
8. **Check Adhesion:** Inspect the sensor's edges to ensure good adhesion. Press firmly around the edges with your finger if needed.

**Enjoy!** Following these steps should lead to a secure sensor that lasts the full duration. Some users even find it difficult to remove after two weeks.

**Hints for Improved Accuracy and Reliability:**
- **Hint 1: Stable Blood Glucose During Initialization:**
- For optimal calibration and accuracy, it's beneficial to have your blood glucose within the normal range (70-140 mg/dL) when starting a new sensor.
- During the initial hours, try to maintain stable blood glucose levels, avoiding rapid changes exceeding 2 mg/dL per minute.
- Rapid fluctuations can trigger error messages like "Sensor error - Please scan again in X hours" as the sensor requires more time to calibrate under such conditions.
- **Hint 2: Soaking the Sensor (Pre-Activation):**
- Many users find that "soaking" the sensor---waiting several hours after insertion before activating (scanning) it---improves startup reliability.
- **Rationale:** Soaking allows the body tissue to recover from the insertion and interstitial fluid to stabilize before the sensor begins taking measurements.

**By diligently following these steps and incorporating these user-proven hints, you can maximize the lifespan, accuracy, and reliability of your Libre sensor.**