Johns Hopkins Diabetes GuideDevices

Continuous Glucose Monitors

Clare J. Lee, M.D., Thomas Donner, M.D.
Continuous Glucose Monitors is a topic covered in the Johns Hopkins Diabetes Guide.

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  • Continuous glucose monitors (CGM) are devices that can measure interstitial glucose every several minutes to inform real-time glycemic values and trends to the user.
  • CGM devices consist of three parts, a sensor, transmitter, and receiver. The sensor is inserted under the skin to check glucose levels in the interstitial fluid. The sensor stays in place for several days to a week after which it must be replaced.
  • The user must calibrate CGM by checking blood samples at least twice a day using a glucose meter.
  • CGM devices must be removed before magnetic resonance imaging or computed tomography, as they can be damaged from these radiological studies.
  • Use of acetaminophen while wearing the sensor from DexCom may falsely raise the sensor glucose readings.
  • CGM devices are safe to be worn on U.S. commercial airlines. For Medtronic Guardian CGM, the transmitter should be disconnected from the sensor while on an aircraft.

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Last updated: June 18, 2013