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How does the sensor compare to a finger prick test?
How does the sensor compare to a finger prick test?

Why it is normal to have different readings between capillary test and CGM

Tia avatar
Written by Tia
Updated over a week ago

Comparing finger pricks and CGM's is not really directly comparable, as one takes a one-time measurement from a capillary resource whereas the other measures continuously from interstitial fluid. CGM's are meant to track trends and see your overall condition with glucose, whereas blood tests give you a snapshot of a given (predetermined) moment. As the CGM measures from interstitial fluid, there is also a slight delay compared to the blood measurement.

When you test your glucose with a glucometer, you measure the glucose directly in your blood. However, the Freestyle Libre sensor we at Veri use measures glucose in the interstitial fluid, rather than in the blood. There’s typically a delay (5-15 minutes between the glucose levels in the blood and the interstitial fluid). Like any data, your blood sugar data is not always 100% accurate. The accuracy comes from of course the sensor, but also from the software algorithms used with it.

An average 10 mg/dL difference between different measurement devices and apps is fairly common since the sensor accuracy is often +- 20 mg/dL. The most important thing about glucose monitoring (if not for medical use) is the trends of your blood sugar - stability, spikes, and fluctuations.

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