Dexcom’s New G4 — Is Now the Time to Buy?

{Editor’s Note: I’m expecting a new G4 unit of my own any day now. I plan to post my own review, and my opinions may differ from our correspondent’s here. We’re all for diversity of viewpoints. -AmyT}

Last month, Dexcom’s fourth-generation Continuous Glucose Monitor (CGM) was FDA approved, much faster than anyone — even the folks at Dexcom— expected. Fifteen days later, I was opening a FedEx box from Dexcom and have been wearing the G4 Platinum 24-7-19 since then. Wait a minute…19?

Yeah, I added nineteen to the name ’cause, you know, as of today, that’s how many days I’ve had it. You can’t be 24-7-365 until you’ve worn it for a year, right? But nearly three weeks is long enough to begin to learn its personality, its strengths, its weaknesses. To judge how much of an improvement it is over its predecessor, and to and help you answer the question: Is it right for me?

What to Love

Let’s face it, she has a pretty face. The G4 has an appealing form factor that can be appreciated in isolation, but it really shines when compared to the squashed football look of previous Dexcom receivers. But is the beauty only skin deep? Is this just the same old CGM in a pretty new box?

Not hardly.

The new sensor is better, both in size and accuracy. The new transmitter has a much longer range. The alarm volume options are better. The user interface is better, especially in the display of blood sugar readings. And that’s just the beginning. All better. But how much impact will these changes really make on your day to day life?

The sensor itself is supposed to be 60% smaller, but frankly, a 60% smaller fishing line is still a fishing line. I couldn’t tell any difference, but I never found the Seven Plus sensor to be painful to insert or to wear. Where I could see a difference, however, was in how well the sensor works and how long it works.

The improvements are subtle, but I’m seeing better accuracy with the G4. It’s probably the best of any of the eight different CGM systems I’ve worn. The G4 catches lows more nimbly than its predecessor, and it’s less likely to tell me that I’m low when I’m not. Beyond that, the accuracy doesn’t wane with time. Thirteen days was the longest my skin could handle having a sensor in one spot, but it was working just fine when I pulled it.

Not Tickled Pink

Color, color, everywhere color. Breaking from the past three systems, which were all T-Ford black, the new G4 comes in three colors, showing that Dexcom is paying attention to consumer tastes and trends. But to be honest, I personally can’t get excited about the new colors. If you put your receiver in a case (they’re all black) then you can’t see the color anyway, and if you don’t use a case you’ll eventually use a skin. There aren’t any skins available yet, but I’d put money on the fact there will be soon. So the receiver colors — black, ocean blue, and tickled pink — are a marketing tool at best.

But the G4’s color isn’t just skin deep after all.

The new receiver also boasts a color screen, and I think it’s the first diabetes device to use color intelligently. Both the Animas Ping and the OneTouch Verio have color screens, but the use of color by both devices seems to me much like Dexcom’s use of surface color: It does no more than let the companies boast that they have used color screens. The G4’s color screen, on the other hand, uses a coordinated color scheme where things related to lows are red, highs are yellow, and situation normal is white.

This color scheme carries across alarms, system status, and more importantly to the ever-updating trace lines that show your recent blood sugar readings. The lines change color when you cross your high and low junctures. A glance at the screen shows you how long you’ve been low or high.

While the receiver status icons are a bit crowded at the top of the screen — a departure from previous models where this info was on the right-hand side — I find the monitor easier to read and I find the “trace” lines of my recent blood sugar meanderings cleaner-looking and easier to view.

But given the battery-sucking reputation of color monitors, what does this color screen cost us in terms of battery life? Like it’s father and grandfather, the G4’s receiver is rechargeable. Surprisingly, unlike previous Dexcom CGMs, the charge actually holds for a decent period of time — well over seven days per charge for me so far.

What to Hate

In the minus column, the new G4 has some disappointments, most of which are things that are missing, rather than things done poorly.

Chief among the things missing is the lack of time-based alarm thresholds, so we can have different high and low alarms at different times of day, and the lack of predictive alarms.

The Medtronic Revel and Guardian CGM systems have this pair of features. But they also have a much larger and less accurate sensor, with a three-day wear indication, and an almost inaudible alarm tone. Even so, these two features combined are so powerful that if you can hear the Medtronic alarms at night, you’re probably better off using their system. Had Dex adopted this pair of features, they would’ve blown Medtronic out of the water, IMHO.

Dexcom also continues its tradition of lousy cases for their great gear. You would think people that smart could come up with a good case. Or why not do away with the case altogether? Why didn’t they design the G4 with an optional belt clip like an insulin pump?

And lastly, in a case of evolution running backwards, the G4’s transmitter is actually larger than its predecessor and its charge lasts only half as long. That said, I think it’s worth the cost in both size and longevity, as it has bought us a quadrupling of the telemetry range between the sensor and the receiver. The old Seven Plus had an official range of five feet. In the open air, if you were naked, it was a bit better (yes, tested!). But wrapped in blankets on a cold night, it often couldn’t communicate between a PWD and his or her nightstand. The G4 boasts an official range of 20 feet, and to be honest, my house apparently isn’t big enough to trigger any separation anxiety between the two parts of the system.

What Stays the Same… Sort of

Hello. Haven’t we met before? Yes, in a police lineup, you’d be very hard pressed to pick out the G4’s sensor inserter from the old one. Same dental tool from hell.

Another thing that stays the same, but can be altered, is the receiver’s voice. The Dexcom G4 is still noisy, if you want it to be. I’ve always been in favor of a CGM so loud it will wake the dead so that you don’t join them, but not everyone agrees with me.

The G4 has five different noise-making “profiles” to choose from, that range in both volume and in length of tone. I’m also happy to say the G4 makes very different noises for different situations. It speaks a language you (and your loved ones) can quickly learn, and its new voices give it personality.

Should You Get Out Your Wallet?

If you’re a Dex Seven user, should you upgrade? Let me be clear: You’ll have to. Eventually. The Seven is dead and buried and the only real question is how long Dexcom will support it. Obviously, it won’t go away overnight, but I doubt they’ll sell any more transmitters. Will they sell sensors for the old system for one or two years? The new sensors and the old are not compatible.

So I guess the question really is: should you upgrade now?

If you’re out of warranty and insured, your insurance company will buy you a new system, and you should do it. The G4 boasts a mildly more accurate sensor, a smaller receiver, and a transmitter with greater range. Any of those three would make the upgrade worth the effort for most CGMers. But you get all three.

On the other hand, the upgrade for an in-warranty system is about 400 bucks. I think if you’ve got more than six months to go, you should get out your wallet. It’ll be worth it for the improvements, and the cost averages out to about $65 per month. Hell, run one sensor for two weeks during that time and you’ve just paid for it.

But if you’ve only got a few months left on your current warranty, and you’re more-or-less happy with the Seven Plus, I’d wait. The G4 is better across the board, but the improvements are all incremental. Sadly, it’s not a quantum leap. There aren’t any truly mind-boggling improvements — except maybe for the transmitter range.

In short, is the G4 system all it could be? No. Not hardly. Are there things I’d change? Always. But is the G4 better than the Seven Plus? Absofreakinlutely. Is it massively better? No, not on any individual metric; but collectively the improvements add up. Whether you upgrade now or later, it’ll put a smile on your face.