CGMs

CGMs are devices that measure and report your interstitial (fluid between your body’s cells) glucose levels, not your actual blood glucose. This is important because CGM readings for low or high blood glucose may be delayed compared to your blood glucose levels. They provide readings 24/7, can tell you whether your blood glucose levels are trending up or down, and provide high and low alarms.

CGMs use a small sensor inserted under the skin, usually on the abdomen or upper arm, to measure glucose levels. CGMs contain a sensor which measures the glucose and a transmitter which sends the results wirelessly to your receiver, smartphone, or insulin pump.

CGMs are highly accurate, closely matching fingerstick blood glucose readings. However, when measured at the same time, CGM readings may show a slight delay compared to blood glucose meters, as they measure glucose in your interstitial fluid rather than blood glucose. Accuracy may decrease immediately after eating, during intense physical activity, or when glucose levels fluctuate rapidly.