Continuous Glucose Monitoring Systems (CGM): What do I Need to Know?

by Linda Kerr, RN, MSN, NP, CDE


Q: What is a continuous glucose monitoring system (CGM)?

A continuous glucose monitoring (CGM) system is an FDA-approved device that records blood sugar levels throughout the day and night. Current devices include the Medtronic MiniMed and DexCom systems. The devices are used to measure average blood sugars for up to three days, while the person with diabetes continues to perform their daily activities.

Q: How does the CGM work?

The system may be worn with or without an insulin pump. A tiny sensor is inserted under the skin to check sugar levels in tissue fluid. The sensor stays in place for several days and then must be replaced. A transmitter sends information about sugar levels via radio waves from the sensor to a small wireless monitor.

Q: Why would I need a CGM system?

There are two (2) ways for you to take advantage of the system. It may be ordered by your physician as a three day evaluation of blood sugar trends, with a start and stop in your doctor's office. Or your physician may prescribe the device as a personal daily use system. Continuous blood sugar results may assist you and your physician to identity patterns and trends related to exercise, meals, stress, diabetes medication regimens, etc. It may even reveal dangerous overnight lows.

Q: Do I still need to use my Glucometer?

Finger stick blood sugar readings and CGM sensor sugar readings rarely match identically. There is an expected 20% or more difference between the fingerstlck and sensor result. Therefore, it is not a replacement for standard blood sugar monitoring using your glucometer. It is only intended for use to discover trends in blood sugar levels, and to warn of dangerously low or high blood sugar levels. Current versions will also warn of rapid changes in blood sugar readings.

Q: What else should I know about CGM?

For more information and tips for success with use of this device, please ask your Physician or Certified Diabetes Educator (CDE). You may also benefit from having access to individuals using the CGM as a daily personal use device. For example, many people who attend Insulin Pump Support Groups also wear this device. One such Support Group is located at Long Beach Memorial Hospital. Meetings are scheduled for the second Monday of each month, in the 5th floor classroom, from 6:30 – 8:00 pm. For more information, call 562-933-5070.