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We last wrote about using the DexCom SEVEN continuous glucose monitor (CGM) in Test Drive of diaTribe Issue 5. Since then, DexCom has come out with its next generation CGM device called the DexCom SEVEN PLUS. As a reasonably faithful DexCom user (I’ve had my flirtations with other CGM systems historically), I was excited to be able to test the new SEVEN PLUS. The handheld still looks like the old SEVEN system, and the change in the new version mostly pertains to new software features.

trend arrows

The biggest and most exciting change for me is the introduction of rate of change arrows. These have been available on the Medtronic Paradigm and Abbott Navigator CGM systems and it was only a matter of time before they appeared on the DexCom system. These arrows give you a quick idea of where your glucose levels are headed, and how fast they are changing. They make me much much smarter about what I eat 

(Tartine Bakery sees me less often) and how I exercise (such as it is), etc. There are seven types of arrows to describe whether your glucose is fairly stable (changing less than 1 mg/dl/min) or increasing rapidly (changing more than 3 mg/dl/min) or moderately (changing between 1-3 mg/dl). For some context, a rate of decrease of 2 mg/dl/min means that after one hour, your glucose levels could drop 120 mg/dl! With an arrow like that, there’s no telling twice to test and treat if necessary. DexCom is the first system to offer information on rates of change of more than 3 mg/dl/min.

alerts, alerts, alerts!

The SEVEN PLUS has a number of new features that including new 6-, 12-, and 24-hour screens in addition to the original 1- and 3-hour screens. You can now put in event markers for every-day things like food, insulin, hypoglycemia symptoms, alcohol, illness, stress, and different intensities of exercise. These options allow users the opportunity to incorporate a lot of “real-life” data that could make visits with educators and physicians all the more fruitful. I very, very much like the meal and insulin markers and use them all the time. While I don't use all these alerts, it's comforting to know that they are there if I decide to use them.

menu driven displays

You know how inadequate your own phone can feel if you walk into an Apple store and try out the iPhone? That’s just about how it feels comparing the easier navigation on the SEVEN PLUS to the old SEVEN. It used to take multiple clicks of the down arrow to get to the 3-hour graph menu. Now it only takes a couple of clicks, which to me means that there’s a lower barrier to interacting more with the device. In addition, it’s much easier to insert blood glucose values for calibration (allows a new sensor adjust itself to your body so it can deliver accurate glucose trends) – just a couple of clicks and you are done.

less obtrusive transmitter

While the size of the transmitter has not changed, the new transmitter sports a grey color, which blends in with light colored clothing much better than the previous black transmitter. What I would really love to see is a change in the color of the white adhesive tape that keeps the transmitter and sensor in place. I would go for transparent tape, ideally. It’s nice to have a less prominent transmitter, but it doesn’t help if the tape is obvious under clothing.

suggestions for improvement

  1. It’s still a little painful to insert for me personally, though less than it used to be. The system uses a 26-gauge needle, which is the smallest of all the systems, but maybe it's just the manual action -I know many who don't mind it, but for me, I'd love something I can feel even less!

  2. Rate of change alarms could be even more customizable. Personally, I’d like to have an alarm when my sugar’s changing at 2 mg/dl/min AND 3 mg/dl/min—the new sensor has both, but you have to choose one or the other. And yes I realize not everyone wants all this information – but I’d like it so I know what food really hits my system the fastest. Right now, though, I have it on 2 mg/dl/min because I do want to make sure I turn the insulin on when I see this alert.

  3. I’d like to see bluetooth connectivity for downloads. The WaveSense Jazz Wireless blood glucose meter has this ability – though it’s not yet approved - and it would be great to see it transferred to continuous glucose monitors. Having this capability would make the download process much simpler since it wouldn’t involve time spent looking for lost cables, or disconnecting other USB devices.

  4. Please make the next DexCom compatible with my Mac. Seriously these are the two devices I use most and it would be great if they could “talk” to each other without the need to download complicated Virtual PC software like Parallels.

Overall, I’m very optimistic about the SEVEN PLUS. I think that however much I loved the SEVEN, the SEVEN PLUS really represents a great improvement over the first-generation SEVEN, and both the trend arrows and the rate of change information in particular are big steps. I’ve found that the trend arrows really help me to improve my management—I got really good at not checking my blood glucose after eating cake, and then I got good at not looking at my CGM for 9 hours, but it’s awfully hard to ignore two arrows straight up (as long as you’re looking at your CGM)! It’s good for DexCom that they’ve integrated this feature, and now patients can get trend arrows regardless of the CGM brand they choose.

DexCom is currently running an upgrade promotion: if you are a SEVEN user and your current system is still under its 1-year warranty, DexCom will give you the new system for a reduced price of $199. This offer is valid from May 18th to June 30th, 2009. Otherwise, right now DexCom is selling the new system for a special introductory cash price of $799--the list price is $1248. To learn more, call 1-888-SEVENGO, and if you’re not a current DexCom user, speak to your healthcare provider about a prescription.