Abbott's Continuous Glucose Monitor Navigator Approved

Gretchen Becker Health Guide
  • Abbott's Navigator continuous glucose monitor (CGM) has finally been approved by the Food and Drug Administration. The device was approved in Europe last June, but US FDA approval has been stalled for several years for reasons that are unclear.


    Every month or so, it seemed, there would be an announcement by Abbott that FDA approval was expected "soon," and some people began to think it would never happen.


    But now it has, and the Navigator will be available for purchase sometime later this spring.


    This means that those who wish to use a CGM will now have a choice of three brands: the Abbott Navigator, the DexCom Seven, and the MiniMed Guardian REAL-Time system. One hopes that competition will bring the prices down.

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    Currently the DexCom kit lists at $800 and includes the receiver, transmitter, software, carrying kit, cables, and battery charger. Sensors are sold in four-packs (about month's worth), for $240, or $60 each, for a total price of $1040. However, they're currently having a special of $295 for the kit if you buy a four-pack of sensors at the regular price (total price of $535).


    Each sensor is FDA-approved for seven days, but many people say they can get them to last longer. The long times aren't recommended, however, because of the risk of infection.


    The Guardian REAL-Time lists at $1339, including a month's worth of 10 three-day sensors. The kit includes basically the same things as the DexCom, except that the free CareLink software is Web based.


    Minimed also sells a CGM system that is integrated with a pump.


    The new Abbott Navigator will be priced between $960 and $1040, according to an Abbott representative. This will include a month's supply of six sensors and presumably the same accessories as the other brands. Sensors alone will cost $360 to $390 a month.


    All the systems basically do they same thing. They insert a sensor into the interstial fluid in your subcutaneous fat. The sensor measures your blood glucose (BG) level every few minutes and transmits that information to a receiver that is about the size of a small insulin pump. The receiver displays the BG level on the receiver and also shows trend graphs of your BG levels for the past hour, several hours, and up to 9, 12, or 24 hours, depending on the brand.


    The devices have alarms that sound when your BG levels go too low or too high (you can determine when you want the alarms to go off, although there may be a low-BG alarm that you can't turn off). The Navigator and the Guardian also have trend arrows that tell you if your BG levels are steady, rising, or falling. The current version of the DexCom does not have the trend arrows.


    The BGs can also be downloaded to software that allows you to print the results or do various manipulations of the data.


    In order to calibrate the CGM receivers, you have to let it know what your fingertip BG level is a certain number of times a day. The new Navigator has a Freestyle BG meter built into the receiver. The Guardian has you input the BG levels manually. The DexCom currently uploads BG levels with a cable from an Ultra BG meter. A new version of the software for the DexCom due out in June will allow you to input the numbers manually so you can use any meter.


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    Other features of the various systems can vary slightly, so you should investigate thoroughly if you're thinking of buying one of these devices. They're also constantly upgrading their systems. This may mean a further investment in the basic kit (DexCom's upgrade from the STS system with three-day sensors to the Seven system with seven-day sensors [which also cost twice as much] and better software cost $150). But they're also constantly adding new features.


    These devices can be wonderful, and some people have seen their A1c's drop almost a full point simply by using them. But they're expensive, at almost $8 to $10 a day for the sensors plus several regular strips a day for the daily calibrations. However, if you're already testing 8 or 10 times a day, the CGM sensors may cost about the same, from an insurance point of view.


    Those who have type 1 diabetes, especially those who have hypoglycemia unawareness, may be able to get their insurance to cover the devices, but you might have to fight to get coverage.


    I have used a DexCom CGM, thanks to a generous friend, and I tried a Guardian CGM for several days as a trial at my endo's office. I found that each one had pluses and minuses. With the DexCom, I get a lot of false lows. You can't turn the alarm off at night, and it keeps waking me up and telling me my BG is 48 when it's really 85. That can get annoying. But it's also wonderful to reach in my pocket and pull out the receiver and look at a graph and know if I'm heading down or heading up, even if the actual number on the screen might not be quite accurate.


    Some of the members of a CGM e-mail list that I subscribe to prefer the DexCom and some prefer the Guardian. Many are using the MiniMed version that is integrated with the pump. It will be interesting to see what people think of the new Navigator when it's actually shipping.


    One problem is that all the CGMs measure interstitial fluid, which lags about 15 minutes behind your fingerstick blood when BGs are changing rapidly. So you shouldn't calibrate the devices when BGs are changing rapidly. Even when you don't, sometimes the CGM gives a number that is not correct. So sometimes you'll use even more strips double-checking the CGM readings than you used without.


    Some people don't like the devices at all and prefer to go back to their old systems of regular testing with a regular BG meter.


    So if you're interested in this new technology, look around. Compare features and compare prices. See if you can try out one of the CGMs before you buy. Maybe your doctor's office has one to loan. It would be even better if they had all the different brands, but probably they won't. Talk to people and find out why they liked or didn't like a particular brand.


    These things can have wonderful results, but they're not for everyone, and they're certainly not cheap. The release of the Navigator gives us more options and should stimulate competition to bring some of the prices down.



Published On: March 13, 2008