Review of my first 10 days with G4

I got pretty lucky in that I was able to get my new Dexcom in the first release round. I’ve been wearing it for about 10 days now, so I thought I’d share everything I can think of for those of you who are on the fence about upgrading or wondering about what awaits you in the next UPS shipment. Happy to answer other questions that you may have, too…

Appearance, Insertion and First Day Thoughts:
The receiver is really clear and easy to read, including in sunlight. There is a slight delay when you click on the center button to wake the display up - it’s annoying, but no more than a second. I hated the too clicky buttons of the 7+ receiver. It felt like they were louder than the alarms! The receiver feels like a nice piece of technology - it feels caught up to the rest of the world. It also fits nicely in a pocket, unlike the egg receiver, which stuck out something awful.

Insertion was exactly the same as the 7+ except the sensor wire and needle felt thinner. I’ve only ever felt a pinch of pain with insertion, and the pinch was definitely less with the new sensor. I’m happy with that. I am less happy with how thick the transmitter is. It’s twice as thick as the old one, and it sits pretty high in the sensor pod/platform. I’ve got this first sensor on my arm, and it’s definitely noticeable in all sweaters and shirts that I’ve worn. That said, no one has asked me “Are you smuggling drugs on your tricep?” so maybe it’s nothing to worry about. I’ll try an abdomen site next, and if it sticks out too much there, I’ll be pretty bummed.

The first day of readings was not so hot. Lots of false lows (readings of <55 when I was really in the 90’s and steady) and lots of microwaves (lots of little rolling hills within a 30 point range that probably aren’t accurate). These all occurred overnight, so I didn’t get much sleep, which may be a reason for the erratic readings. After that first day, though, the readings settled right into line.

I believe that the readings have been within 20% of about 90% of my fingersticks for the life of the sensor so far. The readings tend to be a little lower than my meter, but again, within a reasonable range. This is a good hypo warning me, so I’m ok with it, but I’ve fallen into the habit of disregarding the mild hypo warnings because I “know” I’m probably a little higher. This probably isn’t ideal…

This sensor has been really accurate with exercise, capturing my initial spike right away and then the quick fall that follows an hour afterwards. I feel like the arrows have been accurate overall, though I’m surprised by how long hypo treatments have taken to register on the Dex. We’re talking 45 minutes to single arrow sometimes. I’m not sure if that’s sensor placement, my diet, or the general craziness of diabetes, but it was surprising.

Transmitter Range:
All that extra transmitter heft seems to be worth it in terms of signal strength. This thing beams data through walls, around corners, down the hallway. I can leave the receiver in my office, walk down the hall and have a 20 minute conversation, come back and all the dots are still there. It’s never lost signal overnight, which was a problem with the 7+ for me. It’s great. The only problem is that I lose the receiver in my home because I don’t need to pick it up and carry it with me anymore. This is a pretty great problem to have.

I can’t feel the sensor wire at all. It was a little achy the first two days, but that may be because I don’t often use arm sites. The adhesive seems as strong as the 7+. I’m on day 10, and it has come up about 80% on one side, but is mostly down on the other three sides. A little tape should fix it for a few more days. To prolong tape life, the only thing I do is make sure to dry it off really well after I get out of the shower - kind of “squeeze” the water off the tape with the towel - that’s it.

I don’t think I calibrated excessively. Whenever I noticed that it was 20% or more off, I entered a fingerstick. This usually brought it more in line. I think there was a day or two when it had to prompt me for calibrations because I hadn’t entered one in 12 hours, which I think is a good sign of accuracy.

I restarted the sensor when the original session ended. The past two days have been a little less spot on, but again, within reasonable range in my opinion - 90% within 20% of fingerstick.

I should mention that this sensor coincided with me cutting gluten and most processed foods out of my diet as an experiment, so my range has been much narrower than usual. I haven’t had a reading over 200 since I started this sensor, and no real double ups or double downs (law of small numbers, I guess). Because of this, I can’t attest to it’s high readings accuracy.

I downloaded Dexcom Studio onto my Mac running Windows using BootCamp. The download and installation was easy. I got a few errors that the program wasn’t verified by Windows, but they went away with a few easy clicks, and the machine is still running fine. When I first connected the receiver, it didn’t recognize it a few times and kept saying it needed to download the drivers. After the third driver download cycle, it worked. It’ll probably do that again the next time I connect.

The reports are the same one’s I’m used to. Scatter plots and box graphs and pie charts galore. I remember that the old software would project your A1c, but I didn’t find that option didn’t show up this time around.

Do I like it?
Yes, I do. I was not a faithful 7+ user. The buttons were too clicky. The data wasn’t reliable enough. My hypo unawareness didn’t always require a CGM. I didn’t like all the data all the time. I probably wore a sensor every 6-8 weeks or so, for pattern finding or extra precaution when travelling or working nuttily.

I like the G4 much more. The data is more reliable. It’s more fun to look at. It’s not constantly blaring a lost signal alarm at me. We are better friends.
I’m more confident in the information that it is giving me and my ability to make correction throughout the day and longer term based on that information. Also, it’s pink, and that makes me happier when I look at it.

That’s everything I can think to type right now. Please feel free to ask me any specific questions you may have. I’ll try to answer to the best of my ability/experience so far.

Thanks Lizzie, this is very valuable info. I am still using the Dex 7, and not so frequently because of too many big inaccuracies, and false alarms. Medicare does not cover CGM's so I will have to stick with the Dex 7. I do want to switch to the G4 eventually, and posts like yours will be very helpful.

Good luck with future sensors!!

I agree with a lot of what Lizzie says, and I have found my first G4 sensor to be extremely more accurate than the seven + was. I am on day 9 of same sensor. Most of my Dex readings are within 10 points of my meter. Day one was pretty accurate as well. My rep told me to calibrate more often on day one and try to get some lows and highs, which I did snd I think that helped. I also have the sensor on my abdomen. No one has mentioned seeing it through my shirt, and I think I am more aware of the thicker transmitter than anyone else. All in all, I think the G4 is a huge improvement over the seven.

I'm very interested in how you got the program working on the Mac. I'm a computer illiterate, so can you tell me step by step what you did? Private message would be OK, too! Thanks!

Well, step by step, I asked my boyfriend "Can I install this dumb Windows only program on the Windows side of your mac?" Then I started the computer in Windows and downloaded and installed the program.

Since that's not very helpful, here's a bit more detail, though I'm not an expert at all. If your Mac is running Leopard or later, it comes with a program called Bootcamp. Follow the instructions found here - to install a purchased (or stolen, whatever you want, you just need the disks) copy of Windows onto your mac. Following installation, you now have the choice of whether to start your computer with the Mac OS or Windows. You just need to hold down the option key right after you press the power button at start up. A gray screen with an icon for Windows and an icon for OSX will appear. Pick Windows, then open Internet Explorer and go to to download Studio (It's under the Products menu). Download, install, say yes or ok to every window that pops up. To switch back to the mac OS, you have to restart and hold down option again. That should do it. First thing you have to do is buy, beg, or steal a copy of Windows.

Hope that's helpful.

"We are better friends."


I'm playing my G4 pretty much by the book in terms of calibrations, and I am finding it to be more accurate than my 7+. I wore one for two weeks and it never wavers -- not at the beginning; not at the end. Fine all the way along.

My exercise tends to make my sugars go wacky. Today I rode 13.2 miles on dirt, climbing 2,470 feet along the way, burning 1,396 calories in 1 hour and 45 minutes. I hit rock bottom at the top of the climb, and knew I would pay the (low) price, but offset it with Sport Beans and a bit later with some Shot Blocks. Alls well in the end though -- the G4 is tracking everything fine, even my post ride highs. :)


I'm loving the G4 as well, for many reasons but mostly the hugely improved accuracy. When the seven + yelled at me during the night, my first thought was always..another false low, and I was often right. I'm dealing with the consequences of steroid injections/BG right now so it's been challenging keeping my BG in line. The G4 woke me yesterday morning and read 43; my meter said 45. I won't ignore it or be tempted to throw it!

Meal spikes/hills are much more accurate as well. It doesn't seem to have the 10 minute lag time to catch up with fingerstick readings. Doesn't make sense but I'll take it! I'm calibrating when it more than 15% off. The calibration alarm now is 12 hours from the last calibration, not 12 hours from the last time it ASKED for a calibration.

I've found it equally accurate in the 150-160 range (as high as I've gone) as well as the middle ranges. The battery seems to last longer, and there's a nifty little cover that slides over the micro usb port when not in use. I got to day 10 before I pulled it out in my sleep.

I did stick a label on the back that says Medical Device, with my first name and phone number. It looks so much like an iPod....

I agree with everything Lizzie said about appearance/usability. The scrolling is improved as well, and I do like the pink ;)

I'm just four days into my G4, and my comments would echo yours, except my "accuracy" has been excellent since the first reading. I started the G4 after work last week...and entered the first calibrations at about 10 pm. Something I would have never done with the 7 Plus because I found it was always a poor performer the first day. But the G4 was good that first night and has continued.

I wear the sensor on my abdomen, and the thickness of the new transmitter initially felt odd, but I have gotten used to it.

I'm glad I was able to upgrade. After almost 4 years with the Seven and Seven Plus I was ready for a change.

Lizzie - Thanks for the comprehensive review. I'm on day 12 of my first sensor. The accuracy seems very good but I have not kept track of the overall fingerstick/G4 correlation. After reading another thread here regarding calibrations, I cut way back on the number of calibrations and let the receiver tell me when it wanted one. The accuracy seems to be better now. The biggest thing that sticks out is the absolute lack of data-dropouts. Other than my startup day and the day 7 two-hour blackout/restart, my system has not missed one data point. Very impressive.

I added a separate post this morning to inquire about others experience with the increased range and impressive lack of data dropouts. Your experience on this aspect agrees with mine.

I do wish my first four days were as good as your Lizze. I’ve been wearing my 7+ on one side and my G4 one the other for three days now. With the 7+ I’ve had two cases where the reading was off by more than 80 points, but this was not unusual so I accepted it. However, I was hoping the G4 would be much more reliable. Alas, not the case. I’ve had at least four cases where it was off by more than 80 points and countless times where it’s been off by more than 40-60 when the 7+ was within 10-20 of a finger stick. This is especially disappointing given that my old Freestyle Navigator, which I used for almost four years, was never off by mor than 20 points. NEVER!

If anyone has suggestions I’d love to hear them. In the current case both sensors are on my abdomen about 8 inches apart. I never calibrate when rising or falling significantly. Never inject close to the sensor. What is strange is that it will track for a while and then deviate wildly for no apparent reason. HELP!