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A continuous glucose monitor (CGM) is a device that you attach to your body to read your glucose (sugar) level any time at home. CGMs measure the amount of glucose in the fluid between your skin cells, called interstitial fluid. If your glucose is too low and you don't notice it, some CGMs can alert you in time to get treatment. Your doctor may also recommend using a CGM to help you stay in your target glucose range.
CGMs have several parts.
You wear one part—the sensor—against your skin. It has a tiny sensor that stays under your skin and constantly reads your glucose level. An rtCGM sensor sends this information to the other part of the monitor (a wireless receiver or smartphone app). Some insulin pumps include a built-in rtCGM receiver. An isCGM has a wireless reader device that displays your glucose level when the sensor is scanned with the reader device or smartphone app. You can get a reading whenever you need it. You can view the stored data to help you identify trends in your glucose level.
There can be a 5 to 15 minute difference between an interstitial glucose level and a blood glucose level. If your glucose levels are not changing quickly, there may be little difference between your interstitial glucose level and your blood glucose level. When your glucose level is changing quickly, such as after eating a meal or treating a low glucose, there can be delays in getting an accurate reading from your CGM.
All this detailed information gives you and your diabetes team a better idea of what your treatment needs are.
CGM technology is always changing and getting better. Here are some things to know about most CGMs. These may not apply to all systems.
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Adaptation Date: 10/5/2023
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
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