To Calibrate or Not to Calibrate? Understanding the Basics
The LinX CGM System is designed to provide accurate glucose readings and replace the need for routine daily fingersticks for diabetes management decisions. However, the system also includes a calibration feature. Calibration is a process where you enter a blood glucose value from a fingerstick test into the app to help align the sensor's readings. It is a tool to be used thoughtfully, not frequently, to ensure the system remains as accurate as possible throughout the sensor's life.
When Should You Consider Calibrating?
While you can take fingerstick measurements at any time for your own peace of mind, calibration should be reserved for specific situations where you observe a notable and consistent difference between your sensor readings and your meter readings. The user manual recommends considering calibration in the following scenarios:
- When Symptoms Don't Match Readings: If you are experiencing clear symptoms of low glucose (such as palpitations, hand tremors, or sweating) but your sensor reading is still in the normal range, you should always confirm with a fingerstick. If the fingerstick confirms a low, you can then use that value to calibrate.
- To Confirm Before Treating Highs or Lows: When your sensor reading indicates you are low, high, or approaching those zones, you may wish to confirm the value with a fingerstick before taking corrective action (like eating carbohydrates or taking insulin).
- When There is a Consistent Discrepancy: If you notice that your sensor readings are consistently and significantly different from your fingerstick values. The manual provides a specific guideline: if a reading is more than 20% higher or lower than your fingerstick measurement, you should check again after 2 hours. If this second check still shows a discrepancy of more than 20%, you can calibrate the sensor.
To put the 20% rule into a practical context, if your fingerstick reading is 150 mg/dL, a 20% difference would mean your sensor is reading below 120 mg/dL or above 180 mg/dL. The recommendation to wait two hours and check again is important. It helps confirm that the difference is due to a consistent sensor issue rather than a temporary physiological lag caused by a rapid glucose change. If two checks, performed two hours apart while your glucose is stable, both show a significant difference, it is an appropriate time to calibrate.
When NOT to Calibrate: The Importance of Stable Glucose
The timing of calibration is just as important as the reason for it. There is one critical rule: Do not calibrate when your glucose is changing rapidly. This includes times shortly after a meal, after taking an insulin dose, or during or immediately after exercise.
Calibrating during a rapid change is like trying to set your watch while on a moving train. Due to the natural lag time between blood glucose and sensor glucose, entering a fingerstick value during a period of rapid change can actually confuse the system's algorithm and make the sensor less accurate. For this reason, you should also not calibrate within 15 minutes of consuming carbohydrates or injecting insulin. Always wait for your glucose trend to stabilize before performing a calibration.
The Step-by-Step Calibration Process
If you have determined that calibration is necessary and your glucose is stable, follow these steps:
- Perform a fingerstick test using a clean, reliable blood glucose meter.
- Within 5 minutes of performing the test, open the LinX app.
- Navigate to the Blood Glucose (BG) Dashboard.
- Tap the "Calibrate" function.
- Use the slider or input field to enter the exact glucose value from your blood glucose meter.
- Tap "Calibrate" again to confirm and complete the process. The value used for calibration should be from a test performed no more than 1 minute prior to entry, though up to 5 minutes is acceptable.
Recording vs. Calibrating
On the BG Dashboard, you will also see a "Record" function. It is important to know the difference. "Record" simply logs a fingerstick value in your history for your own reference; it does not affect the sensor's readings or algorithm. "Calibrate" uses the fingerstick value to actively adjust the sensor's algorithm.
Next Step: Every sensor has a limited lifespan. The next guide covers the end-of-life process for your sensor, including how to properly remove, replace, and dispose of it.
