Learning About Continuous Glucose Monitors (CGMs)

What is a continuous glucose monitor?

A continuous glucose monitor (CGM) is a device that you attach to your body. It reads your blood sugar (glucose) level, day and night. If your blood sugar 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 blood sugar range more consistently.

How is a CGM used?

A CGM has several parts.

You wear one part—the sensor—against your skin. It has a tiny needle that stays under your skin and constantly reads your blood sugar level. It sends this information to a wireless receiver. The receiver can tell you if your blood sugar goes up or down and how fast the blood sugar level changes. And you can view the stored data to help you identify trends in your blood sugar level.

Some insulin pumps include a CGM. In this case, the insulin pump is also the receiver.

The readings from the CGM can help you decide what to eat and how to exercise. And they can help you know how much medicine to take. You can note on the receiver when you do these things. That way you can see how those activities affect your blood sugar throughout the day and night. All this detailed information gives you and your doctor 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.

• Sensors need to be changed. Depending on the system, you may need to change the sensor every few days. Some systems have sensors that last 10 days.
• Some CGMs will require that you prick your finger to confirm the CGM's accuracy.
• Some substances like acetaminophen (Tylenol), alcohol, and vitamin C can affect the results in some CGMs. They may make the readings higher than they actually are.