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Dexcom G4: Second Impressions.

It's been three and a half weeks since my transition to the Dexcom G4 system, and I've finally burned through the first box of sensors. (Because I live in fear of the frigging rash, so I immediately pull a sensor once I hit the seven day mark, and I also had to pull one early because I scraped it off while traveling. Going forward, I expect a box of sensors will last me 28 days.) With the first month behind me, I have a few updates to my initial impressions.

The Receiver.  The receiver is still badass. I really do love the smaller size, especially for things like going to the gym. It fits neatly into my meter bag, and it's not this gigantic, intrusive device that I have to whip out at meal times. It's discreet and looks like any other modern device of the 21st century (dagnabit).

The Transmitter.  The f&*k? This thing is big. It's weird how it's "just a little bit bigger" than the old transmitter, but I notice the difference often, even after a month. I ran into this same problem when I switched from the Minimed to the Animas pump. When you're wearing a device every, single day, you become used to every aspect of it, from the curve of the corners to the way the pump clips sticks up ever so slightly ... you know the shape and the experience of it by heart. Which is why the new transmitter is mucking with my head, because it's a whole new set of angles and curves to adjust to. Even though I know the G4 is progress in the right direction, for this CGM, I do not like the new transmitter for it's size.

The Alarms. I do really, really like the alarms. They're louder. The low and the high one sound completely different from one another. The receiver-in-the-glass trick still works fine. I remain a fan of the G4 alarms.

Accuracy. Being 100% honest, the accuracy for me on the G4 isn't great in the first 24 hours. I rely on my glucose meter and fingersticks for that first day (the four I've experienced, so far, anyway), and I see numbers on the Dex that are sometimes as much as 80 points off from where I'm actually clocking in. However, I hope that changes as I move forward, and maybe the first few sensors had some issues in my body. I'm willing to let the first 24 hours fly because the accuracy going forward is scary. Spot-on. I see my meter and the Dex as almost mirror-images of one another, often only off by a handful of points. I see matchy-matchy numbers several times throughout the week. After the first day, I trust the G4 implicitly. And that's a really useful thing, especially as I add more miles to my workouts and have very unpredictable sleeping schedules. (Note: The photo below is from day one, Hour 8 of a new sensor. Maybe things are changing for the better in those first 24 hours?)

And this was Day One. Maybe the tide is turning?

Randoms. The carry case provided by Dexcom looks more like something fit for Man vs. Wild (Bear Grylls is a fox, which makes this too many animals in one sentence aside.) than for life. I am looking forward to the silicone cases that I'm sure are coming for this receiver. Hopefully they arrive before I drop this thing onto the bathroom floor and it shatters into a thousand expensive pieces. Also, I still think the battery life is excellent, and I've charged it only three times in the last four weeks. (That's big, since I LOVE to click the button and look at the graph.) I've yet to download anything to the software (because I have a Mac) or to Diasend (yes you can ... more on that in a bit), so I don't know how that shakes out yet, but I'm curious to have fifteen minutes to myself to find out.  (See also: Birdy starts "school" this week, wherein I plan to reclaim my inbox.) (And this is the end of my parenthesis excursion.) (Or is it?! Dun dun duuuuuun!)

First impressions are behind me. Second impressions are logged. Hopefully third impressions include "Hey, the accuracy improved in the first 25 hours!" and "Wow, what a lovely case for the Dexcom that keeps it safe from Sparling-inspired destruction!"

[Dexcom disclosure]


weird. I'm on my first one still, and it has been within 10 points since the first calibration. compared to the 7+ which took 2 full days to sync. also, get a vera bradley ID case like the rest of us already.

And I too hate the transmitter.

Same same! I concur :) Our accuracy hasn't ever been spot on in the 1st 24 hours -- with the SEVEN or the G4...so that's not anything new for us, but after the 1st 24 hours...GAME ON!!! This thing has been S P O T on.

Now I just need to keep the sensor on for longer than 4 days....(which, to be honest, doesn't happen with ALL the sensors, but so far we've lost 2 before the 7 day mark, so......)

Yep, I've been uploading my Dexcom systems to Diasend for a month or so now, but only the BGs you enter into it for calibration or other "events" that I've seen. I'm hoping they release the "CGM" tab soon!
Also, I hate the case too. I do hope they have a better solution soon!!!!

What's this? A Vera case for this???? We need two of these... can someone post a linky?

Amy - a bunch of us use these. They were more practical for the Seven+ but the G4 fits, with some extra space

Our first sensor was flakey the whole week (100-200 points off), which nearly gave me a heart attack. The 2nd sensor was flakey the first day but has settled in nicely. Agree r.e. the case - with an active small child, our 7+ receivers never lasted long without a silicone casing, and I'm worried we'll wear through this one. Fingers crossed the rashes stay away from you!

The issue with the transmitter being bigger is precisely why I haven't switched! I hated how the Seven+ transmitter looked on me, so when I saw the G4 was bigger, I knew it wouldn't work...

we are still in the 'processsing' phase with Bean's G4. so looking forward to having some real experience with this thing!!

I'm curious about your statement about not downloading because you have a Mac. I'm dumbfounded that the software for Charlotte's OmniPod is not compatible with the Mac - we've been unable to download her numbers, a huge miss in my book (yes, we're got a virtual PC running on the Mac and have spent countless hours with customer service to no avail). I'm ready to contact Apple to complain, since it seems the issue is on their end. Have you had similar problems? I'd love to get some insight and ammo for my next steps. Thanks!

I like the new Diasend tab that includes the CGM tab. It's nice to have my pump, meter and Dex all on the same page and the comparison between the data is helpful. There is a problem though. If you enter carb intake on both your Dex and into your meter, it adds them up, so you end up with double the carb intake. I freaked out the first time I saw this, but hen realized it was adding them.

Kerri, I have been reading many G4 reviews on tudiabetes.org, but yours is much better. Thanks so much!!
I am still using the Dex7+, but only when I really need it. Medicare does not cover CGM's. I will probably buy the G4 system someday. You have convinced me that it will be worth the extra expense.

I'm amazed by how far away you can be! Hubby was in the living room and the dexcom receiver was in the bedroom 2 walls and 30+ feet away and it didn't miss a beat.

Thanks for your review! You give great detail on things that I would be concerned about the unit. Random question...did you use your pump during your pregnancy? I don't have any kids but would like to in the future and didn't know the limitations with using a pump or CGM while pregnant. Thanks!

Thanks for the updated review, the first 24 hours on my 7+ are not too reliable, so I'm used to it. If the accuracy after that is even better, I'll be thrilled! Mine should be here just in time for Christmas :)

Kerri, I agree almost completely with your second impressions. First, I HATE the new size. I understand the why and obviously I'm wearing the DexCom non-stop, but I used to wear it on the back of my hip and I've resorted to primarily my arm because I could not sleep on the thing without creating some major eye opening pain. That said, I wanted to impart some info shared with me by my DexCom rep: He told me that whenever possible, in the first 24 hours of a new sensor, I should do the regular calibration and at least one "high" (over 200) and one "low". This isn't in the manual or anything, but the sooner you calibrate your own numbers for high and low, the sooner the Dexcom catches on. From there on, it should be smooth sailing. Also, as a side note, the week I received my new G4, was the week I had been training for all year. I was running my first half marathon since diagnosis and was just a little bit paranoid about changing systems literally 4 days before the race. All I can say is WOW! While the 7+ was useful in my training, it never really kept up with me on the training runs. I used it more to watch for lows in the hours after exercise (so still VERY useful); however, this G4 stuck within 5 points of my glucometer the entire race! In fact, at one point during miles 6-7 I had trouble with my meter. Possibly because of the salt on my hands, it kept erroring but the DexCom beeped that even with the 20g of carb I had just ingested 2 miles back, my blood sugar was hovering around 70. I decided to trust the G4 and had another gel. About a mile down, there was a water station, I rinsed my hands and tested again. Glucometer: 94 DexCom: 94! Again, I hate the size of the thing, but I am devoted.

How did you get Diasend working with a CGM in the US? The cgm site is ghosted out for US users. We have the subscription because Animas pays for it. I'd like my 19 year old daughter to have all her numbers easily available to us and her medical team (which does use Diasend).

My first attempt at posting seems to have failed; my daughter is upgrading to the g4 from the 7. Also, we started using diasend courtesy of Animas, but the cgm tab online is ghosted out and does not work, even though the software does connect to her 7 and uploads data. Diasend says they don't support cgms in the US and has no idea when or if they ever will.

My DS (15 yo, dxd June 2010) is finally coming around to trying some tech tools after our first "Severe Hypo Reaction" 2 weeks ago. I am in the process of getting his g4 ordered right now. We should have it late next week some time. The size should not bother him because he has not had one before. He is in track. So any tips for using it during running/working out would be helpful. Also, when summer gets here, any way we can swim with it? This has been a VERY HELPFUL BLOG! Thanks and keep 'em coming!

I've been using my new G4 this week. When it works it is accurate most of the time and a very useful tool. I wear a pump. I'm a lawyer in Manhattan and I also teach and train in kickboxing and taekwon-do. The idea of knowing glucose trends is very important to me. I've done manual trending myself with finger sticks and graphs for years. I've had diabetes for 35 years since I was 12. So far the only problem I've encountered with the G4 is that it is not water resistant even though Dexcom says it is. I have had 3 sensor failures in 2 days due to water or steam from taking a shower. Actually one sensor almost failed ( it showed the hourglass and question marks) but then it came back and worked until a shower later in the day totally killed it. There was very clearly moisture under the transmitter. So I think I'll be ok with the G4 as long as I don't shower any more. Today I ordered "shower caps" for $10 plus $15 shipping from Dexcom so we'll see if that helps. This is disappointing because I've never had any shower issues with any of the various pumps I've worn over the years, including the animas ping currently. I should say that Dexcom's tech support has been very cooperative about replacing the failed sensors but I wish I didn't have to call them so frequently.

I've had the G4 for several weeks now, and have had no problems with water, either shower or swimming. I'm still quite displeased with Dexcom's lack of support for using Studio on a Mac. They aren't very nice on the phone, saying basically it's not their responsibility. One would think that someone in the company would suggest workaround using a virtual machine. They could hire a software kid to get it to work i'm, but they just seem to have no interest in being helpful this way. And the fact that you need the software even to simply charge the G4 is really dumb and inconsiderate.

I've been using G4 since the first week of release. It is quantum leaps beyond the System 7 in reliability and accuracy.

I wear the G4 24/7 and usually get 2-weeks from each sensor and have stretched a couple to almost 3 weeks.

I do apply Opsite-Flexfix strips around the sensor to hold in place as the original sticky gives up at about 7-days for me.

Heat and humidity does loosen sticky so may use the Opsite sooner this summer in hot/humid Texas.

Two mechanical failures with the receiver when the selection button and wheel fell off and I also had the USB slider door fall out when the plastic track broke off.

After those two experiences I finally started to use the provided protective case and it works very well.

As for Wayne's comment about needing software to charge the G4. He is wrong and I'm not sure what he is talking about.

Dexcom Studio is the software for collecting data and it works very well.

The G4 is supplied with the necessary USB cable and wall-wart charger to re-charge the receiver and there is NO software involved with that mechanical process.

I've been a T1 diabetic since 1967 and am currently 63. I've been wearing pumps for over 25 years and using CGMS product since the Navigator was originally released.

I'm an aggressive patient in maintaining this disease and don't have any major side-effects ... YET!

I'm optimistic that I'll be able to stay ahead of the curve ... Lord willing.


Nolan K.
Plano, TX

Hi, everyone. Great comments! How many days are people getting out of their sensors before needing to replace them? I'm finding that mine are lasting 6 or 7 days and then I start to get bad readings usually telling me the sugar levels are lower than they really are. For example, today my sensor just told me I was at 95 when a finger stick showed 180. Usually the the sensor and tester are very close (within 10 or 15 points).

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