Demystifying the CGM: Everything you need to know about Continuous Glucose Monitors

By Patricia Stuart

Demystifying the CGM: Everything you need to know about Continuous Glucose Monitors

“I’d give up my insulin pump before I’d give up my CGM ....I really cannot imagine going through my day without it.” 

 ~ Diabetes Patient using an Insulin Pump with an Integrated CGM

 

Knowledge of glucose levels has always been associated with improved glucose control. As much as self monitoring of blood glucose was a major opportunity for improved patient control, a series of glucose snap shots left opportunities to identify missed highs and lows. The introduction of continuous glucose monitoring has been a big step toward the artificial pancreas.

What is continuous glucose monitoring?

Continuous glucose monitoring (CGM) is a glucose monitoring system that continuously check glucose every few minutes, 24-hours a day, and up to ninety days. A CGM system includes the following:

  • Sensor: tiny probe inserted into the fat tissue
  • Transmitter: communicates with the sensor, while sending results to a receiver
  • Receiver: receives data from the transmitter, processes data via algorithms, and displays results via graph.

Why continuous glucose monitoring?

Why CGM? Better question, why glucose monitoring? If information gathered via glucose monitoring is helpful, wouldn’t hundreds of glucose checks be more helpful? Continuous glucose monitoring gives you much more information.

Additionally, continuous glucose monitoring results can be shared with others allowing additional support for a condition that never takes a holiday. The recent integration of insulin pumps and CGMs to allow a coordinated delivery of medication based on CGM glucose levels has provided many with an artificial pancreas-like experience.

Advantages / disadvantages of continuous glucose monitoring

Can you afford CGM?
CGM may or may not be covered by your insurance provider. Without insurance coverage of CGM devices and supplies, the recurring expense of sensors and/or scheduled replacement of transmitters can make CGM a financial concern.

CGM is not “plug and play”
You can’t just connect to a continuous glucose monitoring device and expect miracles. CGM requires a learning curve. Each CGM has it’s own technical aspects that is best understood. Just like a glucose monitor, CGM is a management tool. For those who find glucose management challenging, CGM could translate into a improved quality of life.

CGMs allow discreet glucose monitoring.
CGMs allow a quick glance at a phone or pump to review glucose levels.

CGM provides near real time glucose information.
More than knowing your glucose level at the moment you check, a CGM will display where your glucose has been and suggest where it’s going. This additional information allows the wearer to adjust future actions (food intake or physical activity).

CGM results may have a “lag time”.
CGMs measure glucose in the interstitial fluid vs fingersticks that measure glucose from blood. This may result a 5 - 30 minute period of time until CGM sensor glucose “catches up” to fingerstick glucose results. Lag time can vary by sensor placement. The impact of lag time is minimal when glucose levels are relatively consistent. When glucose levels are changing over a short period of time, it is recommended that a fingerstick glucose be performed before making a treatment change.

CGM does not remove the need for all fingerstick glucose checks.
CGMs may require calibration glucose checks and/or fingerstick confirmation before treating highs or lows.

CGMs can provide problem solving insights and demonstrate things you never knew.
When is a good A1c not indicative of good glucose control? Answer: when that good A1c rest on episodes of low glucose. Only through 24-hour a day continuous glucose monitoring can this be detected. CGMs can not only display “when” something occurred but also provide insightful data to suggest what may have triggered a problematic event. Additionally, CGM can provide feedback to the effectiveness of problem solving skills in response to an event supporting greater understanding of true individualized diabetes management. For many persons living with diabetes, this is the holy grail of diabetes monitoring.

CGM can alert when high or low.
CGMs can provide alerts when glucose levels are high or low. For persons with glycemic unawareness or difficult to control diabetes, CGM monitoring has resulted in greater understanding of glucose excursions. For some CGM users alerts can happen too often or repeatedly at the wrong time creating “alarm fatigue”. These alarms can be confusing, stressful and remove the advantage of “discreet” glucose monitoring.

Are you willing to “wear” a health device?
No matter how great CGM technology may be, it must be attached to someone’s body to demonstrate that greatness. That individual has the inherent right to choose whether or not they want to “wear” the device or if the device is, maybe, just a little “too much at times.”

Clearly more knowledge about individual glucose levels have the potential to improve glucose control and reduce glucose highs / lows, complications, and hospitalizations — all associated with improved quality of life. Yet this technology depends on the human experience to be optimized. While CGM will be the holy grail for many, there will be others that will not see it that way.

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Orignially published on June 2, 2020, updated on June 02, 2020

Topic: Diabetes Management

About Patricia Stuart