The Instinct sensor can be off by about 20% and still be within the commonly cited tolerance, which means the gap can be around 30–60 points when glucose is higher. Public forum posts also describe differences of 20–30 points and sometimes more, especially early in wear or when readings are changing quickly.

Quick Scoop

That said, the exact amount can vary because both the sensor and fingerstick meter have their own error range, so a mismatch does not automatically mean the sensor is faulty. One forum example notes that at a reading around 322 , a 20% variance could be roughly 64 points off.

What people are seeing

  • Some users report the sensor being 20–30 points off.
  • Others report 30–60 points off, especially when comparing to a fingerstick.
  • Early wear can be less stable, and readings may lag behind blood glucose changes.

Practical read

If the sensor is consistently far off, or the difference is causing unsafe dosing decisions, it is worth treating the sensor as unreliable and confirming with a fingerstick. The official support materials confirm the Instinct sensor is designed for up to 15 days of wear, but the public sources I found here do not give a clearer published “points off” number than the tolerance discussion above.

Bottom line

A reasonable real-world answer is roughly 20% off , which often works out to 20–60 points , depending on the glucose level.