Types of Continuous Glucose Monitors

Reviewed by: HU Medical Review Board | Last reviewed: February 2021.

Continuous glucose monitors (CGMs) are another way to check your blood glucose. CGMs offer more reliable, more frequent details about what is happening with your glucose levels than standard glucometers or finger sticks.1

There are currently 2 types of continuous glucose monitors approved for use in the United States for people with diabetes. Both types measure interstitial blood glucose levels, which is glucose found in the fluid between the cells. The types are:1

  • Real-time CGM (also called continuous monitoring)
  • Intermittently scanned CGM (also called flash monitoring)

The differences between the 2 types of CGMs are similar to the differences between a camera and a security video. A camera takes a detailed, single image of something. A security video takes many, less focused frames over a set time.2

In the same way, real-time CGM takes single, accurate “pictures” of your blood glucose at regular times. Intermittently scanned CGMs provide a running “picture” of your blood glucose over time. Both types of monitors can be useful for people with diabetes.2

Any CGM is used along with a standard blood glucose meter and regular A1C tests at a doctor’s office. You need a prescription to get a CGM.2

Best uses for real-time CGMs

Real-time continuous glucose monitors (CMGs) are most often recommended to:1

  • People with type 1 diabetes
  • People with type 2 diabetes who need to tightly control their insulin therapy
  • People who find it hard to recognize symptoms of low blood sugar (called impaired hypoglycemia awareness)
  • Children and other people who need support from caregivers
  • Athletes who have diabetes
  • People who often have high or low blood glucose
  • People who have nocturnal (nighttime) hypoglycemia (low blood glucose)

Real-time CGMs are the most advanced technology we have to monitor blood glucose at this time. These monitors are the only ones that work with an insulin pump and have alarms and alerts when blood glucose reaches dangerous levels.1

Best uses for intermittently scanned CGMs

Intermittently scanned continuous glucose monitors (CGMs) are most often recommended to:1,3

  • People with pre-diabetes
  • People newly diagnosed with type 2 diabetes who are learning how food and exercise affect their blood sugar levels
  • People who need to check their blood sugar several times a day, such as women with gestational diabetes
  • People with diabetes who want more data
  • People who want an alternative to standard glucose monitors and the sticks they require

Intermittently scanned CGMs may provide plenty of data to help people with less serious forms of diabetes or pre-diabetes. Doctors most often use these devices to help patients see the direct connection between what they eat and what happens with their blood sugar.1,3

Several CGM models are available in the United States. The devices are being used by more and more people with type 2 diabetes and prediabetes. All CGMs display your glucose numbers on a small screen that you keep on or near your body. They also send your data to a smartphone or computer.1,3

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