Is keeping tabs on your glucose 24/7 without a finger prick on your diabetes wish list? Well, your wish could come true with a continuous glucose monitor (CGM).
"Continuous glucose monitoring has come through initial growing pains and is ready for prime time," says Gary Scheiner, CDE, owner of Integrated Diabetes Services near Philadelphia and author of Think Like a Pancreas, second edition (Perseus Publishing, 2011); he's had type 1 diabetes for 27 years and wears a CGM nearly constantly. Scheiner adds, "As research continues to show CGM's value and safety, it's gaining wider acceptance by people with diabetes (PWDs), health care providers, and even health care plans."
Scheiner says the advantage of continuous monitoring is not the plethora of glucose readings, but the ability to observe and analyze glucose trends and learn to make better decisions about food, insulin, exercise, and more. Another benefit is being able to set high and low glucose alerts to fix and prevent problems before they happen.
Approved and Available CGMs
Two CGMs are currently approved by the U.S. Food and Drug Administration (FDA) and available on the market.
Dexcom's G4 PLATINUM, approved by the FDA in late 2012, is an independent device, meaning people who wear a pump, take insulin by injection, or take other blood glucose-lowering medications can use it. This device is Dexcom's fourth-generation CGM and will replace their SEVEN PLUS model. People who currently use the SEVEN PLUS model can continue to get the necessary supplies or upgrade to the new G4 PLATINUM at a cost.
The other CGM is Medtronic's MiniMed Paradigm REAL-Time Revel system. The Revel is an insulin pump that integrates the CGM by using the pump screen to double as the CGM receiver.
Three other related devices are approved and available:
- Medtronic's Guardian REAL-Time CGM is a CGM only. The receiver looks like the Revel insulin pump but is only a CGM receiver.
- Also from Medtronic, mySentry is a remote monitor that allows a child's parent or caregiver to see and hear CGM results from another room. It only works with the Medtronic CGMs.
- iPro2 is a CGM for use by health care providers to gather a complete picture of a PWD's glucose control over three days. Providers can use this data to inform diabetes treatment changes. The iPro2 is "blinded" so the person wearing it doesn't see the real-time glucose results until the three days of readings are collected. Then the data is downloaded, reviewed, and analyzed by the provider and PWD to determine actions to take.
When researching the latest and greatest in CGMs, note that companies constantly work to improve accuracy and ease of use of their devices. Often one generation is on the market, one is at the FDA for review, and more are in research and development to become the next-generation device. This is good news for PWDs. But before buying a CGM, ask the device manufacturer about the timeline for approval and availability of their next device.
CGMs and Their Parts
CGMs contain three parts:
- Glucose sensor: Placed just under skin by the user or caregiver with an inserter. The sensor contains an electrode that creates a small current to detect changes in glucose levels.
- Transmitter: Connects to the sensor to send results to the receiver. The Dexcom transmitter has a built-in power source that lasts a year and doesn't require batteries. The transmitters on Medtronic's CGMs (Revel and Guardian) use a rechargeable battery, which the company recommends rotating and recharging about every three days when the sensor is changed. The Medtronic transmitters last about a year.
- Receiver: Shows the glucose results and allows you to operate the CGM. Dexcom's receiver is a handheld device. Medtronic's receiver is within the pump.
- Software for data analysis: All CGMs integrate with proprietary software, which allows the user to track trends and communicate data to health care providers.