What is isCGM?

Intermittently scanned continuous glucose monitoring (isCGM), enables you to check your glucose levels without routinely pricking your finger. Instead, a small sensor sits on your upper arm. You scan the sensor using the handset or a mobile phone. As long as the sensor is scanned properly, it automatically measures and continuously stores glucose readings day and night.

The difference between blood glucose and sensor glucose

Unlike current blood glucose meters, the FreeStyle Libre 2 sensor measures the glucose in the body’s interstitial fluid (ISF). Interstitial fluid is the body fluid between blood vessels and cells below your skin, as seen in the diagram below:

Finger prick blood glucose readings and sensor glucose readings won’t always match and in fact, are likely to be different because sensor glucose readings come from the interstitial fluid, not from your blood.

There is a 5 to 10-minute delay in ISF glucose response to changes in blood glucose, but generally, glucose readings in ISF have been proven to reliably reflect blood glucose levels.

What’s the difference between Real-Time Continuous Glucose Monitoring (rtCGM) and intermittently scanned continuous glucose monitoring (isCGM)? 

A Real-Time Continuous Glucose Monitor (rtCGM) is always recording your blood glucose and sending the data to your display device (a handheld monitor or mobile phone) and will alert you when your glucose is low, high or changing according to your own settings. 

With isCGM, it’s only when you scan your sensor that you get your reading and trends, but the Libre 2 flash glucose monitor allows you to set alerts for low and high glucose too. These alarms will go off even if you are not actually scanning when the glucose goes low or high.