Dexcom Monotherapy Report

As I turned off the Guardian I felt a mix of fear, longing, and separation anxiety—tinged with stomach butterfly excitement and a little bit of guilt.

This machine, and her predecessor, have kept me alive since 2005. Oooooo, I like that. Alive since 2005, what nice rhythm and rhyme. I should get a T-shirt made.

And now I’m contemplating kicking her to the curb? On one hand it just doesn’t seem right. On the other hand, what kind of idiot doesn’t use the very best equipment possible when it comes to keeping alive?

Would you like our top of the line parachute, or this discontinued closeout model we have on final clearance sale?

But on day one I left the Med-T sensor in my body and carried the sleeping Guardian monitor in my Go-Bag to work. Training wheels to fall back on during the first few hours, just for in case, as my in-laws like to say. I inserted a brand-new Dex sensor and started my Monotherapy Week.

The Dex inserter, while looking like the dental tool from hell, is actually very elegantly designed, and sticking a Dex sensor into your body is easy with only the slightest of stings. Med-T sensors are ginormous by comparison. If you are putting a kid on a CGM, this alone might be reason enough to choose the Dex over the Med-T.

Sensor in, I drop the Dex monitor into my cargo pants pocket and head off to work. FYI, don’t do this with the Med-T Guardian, you’ll lose telemetry. The Dexcom has a much more robust communication range between the sensor/transmitter and the receiver/monitor; and damn lucky thing too, given that the Dex belt case is sooooooooo poorly designed.

During our morning medical team meeting two hours later, my pants begin to vibrate vigorously. The nurse next to me raises one eyebrow and gives me a funny look. You always have this effect on me, I whisper to her, which nets me a well-deserved punch in the shoulder.

I enter one fingerstick. And then the second one. I love this concept of dual sticks for initial calibration as most meters on the market are pieces of crap, accuracy wise, and most D-Folk are being robbed of the ability to choose their meter brand by their insurance companies. The Dexcom spooled up and so for the rest of the day things went fine.

But that was about to change.

Oh, and before I forget to tell you, the Dex does talk after all. It’s amazing what you can learn if you read the manual (who would have thought?). When you choose the “Vibe then Beep” mode for alarms in the setup menu, the device vibrates and squawks in your hand. So I naturally assumed it would do the same thing in a real-world emergency. Not so. As it turns out, Dex is a polite little girl with a bad temper. First she tugs on your sleeve for attention. If you ignore her, she stands up on her tippy-toes and shouts in your ear. You see, Dex alarms have two phases.

What happens during a real alarm is this: first the monitor vibrates. Vigorously, as mentioned before. Comparing the vibe of the Med-T to the vibe of the Dex would be like comparing a Prius to a Hummer. Not only can you feel the Dex vibe to your bones, you can actually hear it.

Which is why, on my first week+ using the Dex, I thought my borrowed monitor was broken or mute, I caught every alarm in the first phase. If you do not respond to the vibe, in five minutes all hell breaks loose. And she has a gloriously loud voice. Once I got around to reading the manual and learned that this is how she works, I ignored a vibe and was rewarded by hearing her high-decibel voice. More on that later.

I’m mildly annoyed by this approach. If you miss the vibe, and you are low, it is another five minutes before you are alerted. A lot can happen in five minutes. But on the other hand, if you are in a medical team meeting, maybe it is better that only the nurse next to you knows you’ve been into the Christmas cookies on the carb table; rather than the whole room.

My original Guardian was not only loud, but had a great personality. Low and high alarms were very different from each other and my coworkers learned to speak her language, knew whether to tease me or come running with sugar.

Sigh… I actually miss that machine.

When I got home at the end of the first day, I placed the sleeping Guardian monitor in my medicine cabinet and pulled off the Med-T sensor. No life boats. Time to sink or swim with Dex.

Not fifteen minutes later we hit the ice berg.

Instead of the constant flow of quality blood sugar data I had been getting all day I was suddenly confronted with “???” on the face of my Dex monitor. The manual helpfully tells me that this means “the sensor is sending glucose readings that the receiver does not understand.” Oh, that’s just fucking great.

It is now too late at night to put in a new Med-T sensor to replace the one I just yanked out. I feed the Dex a few fingersticks hoping to wake her up, but with no luck.

I throw the stupid monitor into bed with me, and figure my odds of dying in one night of no-CGM coverage are on the low side. Pissed-off, I pull the covers up to my chin and vow to put a new Med-T sensor in first thing in the morning…

A fog horn wakes me at three in the morning. What the f….???

I fumble among the covers to find the source of the racket. A glowing blue light catches my eye. LOW says the Dex. I groan. Yeah. Right. Suuuuuuuuuuure I am. I’m thinking that this piece of junk that crapped out on me earlier has only come back to life with a false low reading. I turn on my bed-side light, and squinting, reach for my Presto.

Click. Snap. Slurp. 69 mg/dl.

Well, I’ll be…

So not only was I actually low, and not only did I sleep through a vigorous vibe, but the Dex’s fog horn actually woke me up. I wonder, would the Med-T’s delicate vibe and pipsqueak back-up voice have woken me up on this particular night?

Since her nocturnal re-wakening, following a full six hours of no data, the sensor has performed flawlessly. It ran the remainder of the full seven days with frightening accuracy. And then I lied to the monitor and told it that it had a new sensor, and two hours later it booted up just fine. We are now two days into a second week. There has been no drop in accuracy. Being poor, I routinely use a Med-T three-day sensor twice for a total of six days, but I find the accuracy is falling off towards the end, especially on the high and low ends. That the Dex sensor can run strong for more than ten days just blows my mind.

Normally, I would not want something in my body more than a week, but I only have this one Dex sensor, and I want to extend the trail as long as possible. I don’t for even a second recommend going beyond seven days to anyone unless it is an emergency. Do what I say, not what I do. See? I’ve always maintained that I’m a better tour guide than a role model.

The body doesn’t like stuff that doesn’t belong there inside of it. It also isn’t so great for your skin to have something stuck on it, suffocating it, for that great a period of time. Leaving a piece of tape of any sort on your skin for too long is a great way to develop an allergy to it, and if that happens you won’t be able to wear a sensor anywhere on your skin for any length of time. OK, end of lecture. Don’t say you weren’t warned.

But on to the week’s highlights. On Thanksgiving, as all of you saw, too much pumpkin pie taxes the ability of the machine. Like the Med-T, the makers of the Dex assume you have no business being in DKA territory, and both devices simply do not work above 400 mg/dl and will only tell you that you are high. I’m actually fine with that. If you are routinely above 400, you don’t really need a CGM. You need a referral to the dialysis center in your area.

Again, like on my first Dex sensor, I was impressed by how responsive the Dex is to changes in my blood sugar. I got used to carrying it in my right cargo pocket (the sensor is implanted on my right stomach). When alarms shook my pants it was fast and easy to fish out the monitor. Also, if I just wanted to know what was happening, it really wasn’t that big of a deal to reach in and grab the monitor. Carrying it in the right-side pocket forced me to use it right handed, and I found it a simple one-handed operation to check in on my diabetes.

I find the Dex’s size big, and the shape ugly, but it is oddly ergonomic and I never had any fears of dropping the device; especially important as this one does not belong to me.

The Dex works just fine 850 feet underground, although the same can’t be said for my diabetic body. What was I doing 850 feet underground? Oh, the day after Thanksgiving we all piled into SweetRide and drove down to Carlsbad to do the Pecos River Light thing and visited the famous caverns. It’s a lot of walking, and of course I had a hypo. Dex alerted me as I crossed my low threshold and tracked my several doses of glucose as I tried to crawl my way back out of it.

Once again, I tried to trip up the system by giving it calibration sticks under circumstances that would give a Med-T sensor a nervous breakdown, and once again the Dex stayed steady and true to my BGL. I’ve been preaching for years that learning to calibrate under the right circumstances is just part of having a CGM, just like more fingersticks is part of wearing a pump (no basal insulin!). But that said, I found it… liberating… to just calibrate whenever I wanted to, rather than only in still water.

I did find it annoying that there was no way to check when the next calibration is due. I also had no way of checking the signal strength coming off of the sensor, what is called ISIG in the Med-T universe. Nor could I scroll back to check specific readings at specific times. You can only look at the crude graphs for a rough idea of your recent history.

I think a good comparison is to look back at where computers were about 15 years ago. At that time the Microsoft operating system was very paternal. It wouldn’t let you in to the depths of the machine. It protected the user. Macs, at that time anyway, gave you wider access to explore, and if you were careless, to do damage.

Dex is a very much more simple platform. You aren’t allowed to do or know much, but you can’t really cause any harm either. I would think that the learning curve would be much shorter for new users.

After some fooling around, I settled on a low threshold of 90 mg/dl with a 30 minute “snooze.” I don’t like having a snooze that long. If you are still “low” after 15 minutes, you better be stuffing more carbs into your face. But 30 minutes is the shortest snooze period after a low that the Dex offers as an option. I choose 90 mg/dl as it was the highest low-setting I could personally use without being pestered constantly with nuisance alarms.

Sadly, I’m rarely below 90, so if I do clock a 90, I’m probably on my way to trouble. With a system that includes a predictive alarm I usually select either 75 or 80 for the low threshold.

On the high end, I was more troubled. On my Med-T Guardian, with its basal-rate style alarm thresholds that allow me to choose my alarms at different levels every hour, I used a 170 during the day and a much higher number at night so my sleep was not disturbed unless the shit had really hit the fan.

In the end, I set the Dex for 220, and that has worked pretty well as a day and night compromise. I could, in theory, re-set it every morning, but the truth is that I’ll either forget to or won’t be bothered too, so it is better to just choose a number and stick with it.

On the high end, I choose a three-hour snooze for highs. This means if I have a high, the system won’t alarm again for another three hours if I stay high. One of the things about the Navigator that drove me crazy was that it was alarming all the time for highs. The fact is, if you are high, it is going to take a while to fix.

During my one week with only the Dex as a crutch, I got very comfortable with it. If I were wearing an OmniPod I could have my diabetes literally in my pockets with nothing on my belt for the world to see. Huh. That almost sounds weird, I’m so used to having a storm-trooper’s worth of gear on my belt.

I was really worried about the lack of predictive alarms, one of the greatest weakness of the Dex system. I still think they should add a predictive alarm on the next gen monitor, but it was less of a big deal in reality than I had made it to be in my head. The sensor is so responsive to change, it almost doesn’t need the predictive alarms. On drops it reminds me of the one-minute-sampling Navigator system.

And the Dex trumps the Med-T when it comes to my biggest bitch about the otherwise fine Med-T system: the complete lack of volume in the alarms. Simply put, you can’t hear the alarms on the Guardian. This is no small problem as any alarm is a potential life-threatening situation.

So I started my monotherapy week feeling apprehensive, insecure, and a little guilty. How did it end?

I am alive and well. And that includes surviving a carb-filled holiday, a traveling mini-vacation with all the diabetes damage that comes with a change of pace, and several life-threatening hypos that I, of course, did not feel.

The system was accurate, easy to use, and friendly. Other than the rocky start up, which also happens in Med-T sensors fairly often, the sensor performed like a champ. I’ve come to like the big, bright, easy to read screen. I’ve gotten used to having to press the frickin’ button to see my blood sugar. And the re-charging is less of a hassle than I thought it would be.

In short, the week went well. Very well. You, or I, could absolutely live a long and happy life with the Dexcom as our diabetes buddy and watch dog.

But will I switch?

Hmmm…..