That’s because sensor glucose readings come from the interstitial fluid (ISF), a thin layer of fluid that surrounds the cells of tissues below the skin, not from blood.
Blood glucose and sensor glucose are closely related but not identical.
A sensor glucose reading always lags behind a finger prick blood glucose reading by about 2.4 
4.6 minutes.2,3
If glucose levels are rising or falling, then the two readings may be different. This is completely normal and to be expected, particularly after meals, after taking insulin or when you´ve been exercising.
When your glucose levels are stable then the two readings may be very similar.
Although the readings may differ slightly, the FreeStyle Libre system is accurate3 and safe to dose insulin from your scanned glucose result.1
No finger pricks… means no finger pricks!1
FREE from finger pricks to dose insulin
FREE from finger pricks to confirm low glucose or going low
FREE from finger pricks when glucose is rapidly changing
FREE from finger pricks to take acetaminophen
FREE from finger pricks for calibration
Know the difference between testing interstitial fluid vs blood glucose by watching this video.
1. Finger pricks are required if glucose readings do not match symptoms or expectations
2. FreeStyle Libre System Performance Data Sheet.
3. Alva S. JDST (2020). https://doi.org/10.1177/1932296820958754
– Images are for illustrative purposes only. Not real patient or Health Care Professional.
– Simulated data for illustrative purposes only. Not real patient or data.
