Comparing red delicious apples to golden delicious apples

I’ve been getting emails asking me how the CGMs of Med-T and Dex stack up against each other. It’s still a little early in the game, but here’s my early thoughts (in no particular order):

Device size winner: Medtronic
I like the size of the Revel. It’s small, and thin, without being too small and too thin. On the other hand, I’ve always hated both the size and the shape of the Dex. Why a flattened football? Beats the hell out of me, but I have a theory. I think they wanted a certain size of screen, which ended up making the device too large. To try and make the device smaller, they cut corners. Literally. They cut off all the corners. But, the funky device size leads to a problem in our next category:

Device carrying options winner: Medtronic
The Dex case is pathetic. Worse than pathetic. Lamentable. Miserable. Pitiful. Wretched. Deplorable. But because of the Dex’s funky size, it’s near impossible to find a third-party belt case for it. I did get a Verizon case for the discontinued chocolate line of phones that sort or works, but it only because the case edges are stretchy cloth, and you can stuff the otherwise-too-fat Dex monitor into it. Dex also makes a silicone “skin” for the monitor if you’re a pocket-type person. When I was wearing cargo pants that was OK, but with jeans it’s an issue. Med-T, on the other hand, has two very excellent options. First, they have a well-designed molded plastic holster with a rotating belt clip (that unfortunately tends to break in the field after about six months and costs $17.95 to replace). I started my trial with this option as I had always loved it with Guardian. However, with Revel, it’s not quite so slick, as you now have the tubing to contend with. The second option is a low-profile clip that holds the device close to your body, the top back of the clip has a wide clothes-pin like thumb rest that makes slipping the pump on an off my belt a snap. I’ve decided I like the clip better than the holster, but I applaud Med-T for including both options in the box with all pumps they sell. I don’t know how well this one holds up in the field, having not used it much before, but replacement cost is $12.96. Oh, right, and Med-T also makes some sport cases and fancy leather cases for you suit-and-tie types.

Dust seal winner: Medtronic
Med-T gear is almost water proof, the same cannot be said for the Dex. Dust gets inside the Dex very easily, probably through the recharging port and maybe though the buttons. It can make the screen hard to read in some light, and makes it look ugly all the time. I hadn’t thought about it until just now, but in related vein, a Med-T unit would survive a dunk into a toilet. A Dex? Not so much so.

Volume, daytime winner: Dex
Dex is the hands down winner when it comes to device volume for alarms, both auditory and vibration. The Dex is louder and longer when it comes to making noise and more… I dunno… more strong when it comes to vibration. The Dex vibe is sex-toy worthy, so intense you can both feel it and hear it. Both companies get two thumbs down for not giving us the option of vibing and beeping at the same time. (Dex does have an option to vibe first and follow up with a beep at the next alarm; and if you ignore a Med-T long enough it’ll try other options to try to get your attention).

Volume, nighttime winner: Med-T (provisional)
If you are relying on the pump by itself to wake up at night, may I suggest you also buy pre-paid funeral insurance? But if you’re using Sentry in addition to the pump, it’s indeed much, much, much louder than Dex.

Screen readably winner: Dex
Assuming we’re talking about the screen on the monitor itself, I gotta say the Dex is better. It is bigger, but the resolution is also better, too. Of course, the Sentry is getting me spoiled and at this point, I think either device screen now looks a little too small for me.

Alarm sophistication winner: Med-T
Dex is a kindergartner and Med-T is in grad-school. Dex has one low alarm, one high alarm, and two choices for rate-of-change alarms. Med-T lets you treat your high and low alarms almost like basal rates. You change the thresholds at different times of the day. You can also select a much wider range of numbers for rate-of-change alarms, and of course, the pièce de résistance is the predicted high and predicated low alarms that make CGM that much more accurate and safe to use.

Insertion device winner: Dex
Med-T’s Sen-setter is an embarrassment. It’s awkward, poorly designed, and doesn’t have the power to implant a sensor in a bowl of Jell-O. Dex, on the other hand, has a very, very good inserter device. It looks scary, and it’s not something you can use intuitively. In fact, you can’t always use it even after spending a looooooooong time with the instructions. However, if someone shows you how to use it, you’ll find it simple enough. It can also be used one handed, so you can wear CGM sensors on your arms; something you can’t do with a Med-T sensor unless you have three hands. Med-T sensors can be put in manually (something you can’t do with a Dex), but the guide needle is on the large side, it scares the shit out of most people, and can actually be painful for others.

Transmitter range winner: Dex
I’ve found that the Med-T transmitter is quite a bit weaker than the Dex. It’s more easily blocked by clothing, bedding, or the bod. I need to wear the Revel pump on the same side of my body as the CGM transmitter is on (i.e.: left leg, left hip; right leg, right hip). With the Dex I could always wear the CGM on my right side, regardless of where I had the sensor.

Monitor charging: tie
Med-T’s power comes from a single AAA, Dex needs a wall every three days. You can actually make pretty good arguments for going either direction, and you can adjust to either one. Frankly, I really prefer a battery. It’s easier to carry a spare, or get a spare, than have to worry about lugging a charger along when traveling. Both devices have reliable battery-strength indictors.

Transmitter charging winner: Med-T
The Dex transmitter, like the original Med-T transmitters back in the day, is a sealed unit that lasts for a year. Unlike the original Med-T transmitters, the Dex one craps out by feeding your monitor funky results rather than just dropping dead. A replacement is about $850, but Dex won’t guarantee it unless you buy a brand new monitor to go along with it. What this effectively means is that the Dex system only has a one year life. Depending on your insurance, this can add up to a whole lot more cash out of pocket. Med-T’s seashell, on the other hand, plugs into a AAA-powered charger. I’ve found 15 minutes every six days (while I’m in the shower between sensor changes) keeps it chugging along very smoothly. Also only warrantied for a year, field reports suggest 2-3 years is a realistic life time, so long as the charging is kept up with. If you take a break from CGM and let the damn thing discharge completely, it will die.

Time out winner: Med-T
Med-T give us the option of leaving your CGM on, at the trace screen of your choice, all the time. This way you can glace at your waist and see where your blood sugar is at. Dex doesn’t give us this option.

Back light winner: Dex
Dex’s back light comes on when you press any button. I can’t recall if I set it to do that, or if it always does. Either way, it’s a very handy option. The screen also lights up when it alarms, helpful for finding it in bed at night. The Med-T requires pressing either one, or two buttons at the same time, depending on what screen you left the monitor on, to light up; and it does not light up when it alarms nocturnally.

But which CGM is more accurate?
Damn, I knew you were going to ask me that. You know, I’m really not sure yet. My first Med-T sensor for this project was actually a slightly expired one I bummed from another user because I wanted to pre-insert it the day before the official start, and I didn’t have the supplies at the time. It didn’t exactly cover itself with glory, but it was expired, so I’m more to blame than it is.

I was trying the whole pre-insertion thing because from past experience I had noticed that Med-T sensors are a little funky on their first day, and then settle it. But the first non-expired Med-T sensor gave me some trouble, too. If you call a night of eleven false alarms followed by a night of seven false alarms “some trouble.” The damn sensor was running well below my fingerstick readings; the opposite of the type of trouble you usually get from CGM sensors. Usually, CGMs run a bit higher and risk missing lows. Throughout my sleep shattered pair of nights I tired calibrating, changing alarm thresholds, stretching the re-alarm times, all in a desperate attempt to get some sleep without risk of, you know, dying in my sleep. Finally, so exhausted and frustrated, I one by one, turned off all the alarm systems. Threshold. Predicted. Rate of change. Then the fucking thing lost signal and woke me up to tell me that, too.

I’ve had better nights.

But since that back-to-back pair of nights, the Med-T sensor performance has been quite good. Now, as to Dex, when I switched to them several years ago, they were spot-on almost all the time, and when there were off, a calibration stick would change and correct the readout in a second. But I’m on my third Dex monitor now, and both number two and number three don’t calibrate the way the first one did—something I’m less than happy with. In recent months I frequently found Dex to be more than 100 mg/dL off from my fingersticks, so often that I was getting a “boy who cried wolf” attitude towards the machine and more than once came very close to throwing it out the window. I was ready to look into hypo alert dogs. And I don’t even like dogs. The errors were in both directions. Sometimes a random fingerstick would reveal me to be in deadly danger than Dex was blissfully unaware of, and other times Dex was screaming that the sky was falling when it wasn’t.

What happened to Dex? I suspect they are victims of their own success. Making sensors is hard work. Trying to predict and keep up with demand is tricky businesses. It’s not like you can just increase the speed of the assembly line or add a weekend shift for a month or two when business booms.

So the answer is I don’t know which sensor is more accurate or more reliable. Hopefully over the next six or so weeks I’ll get a clearer view of how well or how poorly the Med-T sensors are doing their job right now.

Don’t worry, you’ll be the first to know how it turns out.


Next time: But do you LIKE mySentry?