2012 Continuous Glucose Monitors
Sue Leferson uses an insulin pump and a continuous glucose monitor. The newest, integrated model by the same manufacturer is the MiniMed Paradigm Real-Time Revel.
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Continuous glucose monitors (CGMs) constantly measure glucose so you know your level at any given time. For people on intensive insulin therapy, seeing the dips or spikes that happen in response to food, medication, and exercise can help guide daily decisions. All CGMs are made up of three components: sensor, transmitter, and receiver. The sensor slips under the skin and is held in place by adhesive. A transmitter attaches to the sensor, relaying information to a handheld receiver or an insulin pump. CGMs measure the level of glucose in the fluid directly beneath the skin, which is similar to the blood glucose level a typical meter measures.
Not sure if a CGM is right for you, or want to compare features among the three CGMs on the market before you buy? Start by asking the following questions:
Is this CGM covered by my insurance?
For many people, this is the most important thing to consider. Your insurer may cover a specific brand or, if you don't use multiple daily insulin injections or have trouble with lows, it may not cover CGMs at all. If you and your doctor think a CGM will help your blood glucose management, but your insurance doesn't cover it, your doctor can contact the insurance company on your behalf and explain why a CGM is necessary.
Will the CGM alert me if I'm too high or too low?
No one expects you to pay attention to your CGM nonstop, so when you go too high or low, the CGM will sound an alarm. Regardless of which CGM you choose, you'll be able to customize the alarms to alert you when you hit your personal limit. Your CGM will also sound an alarm if your glucose is quickly spiking or dropping. This feature is especially useful with frequent unexplained lows, hypoglycemia unawareness, or both.
How can I monitor trends in my glucose level?
The great thing about viewing your glucose level on a CGM is that you can see more than a static number. Take, for instance, a reading of 120 mg/dl on your meter. Do you know if your blood glucose is steady? Rising? Falling? With a CGM, you can glance at trend arrows that will help you catch previously undetected highs and lows—and better prevent them. If you want a detailed look at how your glucose has been trending over the past few hours (or even over the entire day), you can call up a glucose graph.
Can I note important activities or events that affect my blood glucose?
There are plenty of factors that affect your glucose level, such as how long or hard you worked out, whether you just ate, or if you took medication. The event markers on your CGM will allow you to note your activities. Later, when you review a graph of your levels throughout the day, you should have some clues about why your glucose acted as it did.
What does it mean to calibrate a CGM—and how do I do it?
Think of calibration as a security blanket. Even though your CGM is recording your glucose levels, it's necessary to check with a meter every so often to make sure you're getting accurate readings. A CGM's first calibration happens two hours after inserting the sensor (one brand requires calibration at both the two-hour and six-hour marks). After that, you'll need to calibrate every 12 hours.
How long can I wear the CGM sensor before I need to change it?
Sensors are short-lived. Depending on the brand you pick, yours will be expected to last for three or seven days. Then you'll need to insert a new sensor in a new area of your body.
Does this CGM interact with a blood glucose meter or pump?
Here's where the three available CGMs differ the most. All three communicate with a meter, though one uses a cable and the others connect wirelessly. When it comes to insulin pumps, only one CGM is integrated with a pump system. Medtronic's MiniMed Paradigm Real-Time Revel acts as a pump as well as the receiver for a CGM.
Can I use the data management software on my computer with the CGM?
If you plan to review charts, graphs, and tables created from the data on your CGM, first make sure the program will work on your home computer. Find out whether the software works on Mac operating systems as well as Windows to avoid buying a CGM with software you can't use. Both Medtronic CGMs are compatible with Macs, but as of this writing DexCom's is not.
Deciding whether or not to get a CGM—and then picking among the three CGMs available—requires a little homework. Some people find using a CGM gives them useful information to make food, exercise, and medication dosing decisions. Others see the system as one more thing to add to an already long list of expensive and time-consuming diabetes supplies. Your health care provider and people who wear continuous glucose monitors can help you decide whether you're ready for a CGM. From there, choosing between one model and the next comes down to your budget, lifestyle, and which features will help you most.