Category Archives: Continuous Glucose Monitor (CGM)

Dexy’s midnight run, part 1

These people round here
Wear beaten-down eyes sunk in smoke-dried faces
They’re so resigned to what their fate is
But not us (no, never)
No, not us (no, never)
We are far too young and clever (remember)
Too-ra-loo-ra, too-ra-loo-rye, aye
And you’ll hum this tune forever
    –Dexy’s Midnight Runners

Resigned to what my fate is? Not quite. But I am willing to see what the powers-that-be have in store for me before deciding if I want or need to change it. And if a change is in order, I’ll find a clever way to make it happen.

I decided it’s time to give “Plan B”, A.K.A. Dexy, a try

New Blue DexRather than continue to fight the insurance company battle, I went ahead and ordered the Dexcom G4. (yes, it’s the one that also has “platinum” and “share” in its name, but “Dexcom Platinum G4 with Share” is just as much a mouthful as “Medtronic Minimed 530G with Enlite”, so I’ve decided to shorten the name).

I had weighed the options almost a year ago. Some things have changed since then, some have not.

Still, it seems that so many others have tried it and liked it. And those who didn’t like it? They loved it. So I can’t lose (despite my hesitations), right? After a year of using a loaner 530G (disclosure here), I figured I could commit to a year (the insurance-eligibility period) of the Dexcom G4. Or perhaps 30 days, given the return policy, if I didn’t like it — though that would lead me back to my initial predicament.

The order-process was pretty much painless, and as I expected. The insertion, guided only by the Dexcom-provided videos (because I’m too cheap to pay the $40 copay to visit my endo’s office for proper training) was also pretty much painless. It was still a bit weird-feeling at first, but either the feeling dissipated or I got used to it.

As for my reaction (after wearing it for six days, as of this writing), it’s not exactly what I had expected.


I’d suspected that I would need to charge the receiver. The documentation said I needed to charge the receiver. The documentation said that the battery icon would appear “fully green” when it was charged.

I spent about a half hour trying to figure out if my receiver was charged or not, because all I saw was a vertically-oriented, FULLY WHITE, battery icon. I let the thing charge for three hours, and still had the same thing, so I concluded that either it must be either charged, or broken.

Apparently, the old G4 has a nice-sized horizontally-oriented battery icon which turns GREEN when it’s charged (and has an easy-to-see lightning-bolt symbol on it when charging). But the G4 with Share has a tiny vertically-oriented white icon (which goes to black as the battery drains), I guess to make room for the new Bluetooth icon that may sit next to it.

The documentation hadn’t been updated, and though I’ve seen a zillion Dexcom G4 photos in blogs, I couldn’t find one of the G4 with Share online – presumably because everyone just takes screenshots of their iPhones, which is much easier to do.

Also, over the next few days, I discovered that the Dexcom receiver can’t be charged by a normal USB cord, and my phone won’t charge with my Dexcom charger — which is really frustrating considering I have two identical-yet-incompatible micro-USB cords resting on my nightstand. It also explains why my phone battery is presently dead.

Verdict: disappointing


May 2014 prediction on Insertion: “Intuitive, relatively painless. My CDE says that most patients can do it well without training”
May 2014 prediction on Transmitter Mechanics: “Big and boxy, snaps securely into place. Visually hides sensor.”

This may be true. I took my time to do it right, watching the video with my laptop resting on the bed (I haven’t yet joined the iThing-generation, hence you will find nothing about Share here. Also, the “offical” tutorial videos come with the unit on compact disc, and iThings don’t have CD-ROM drives).

Immediately after insertion, I looked down at the thing and thought to myself:

Big Dex


It stood out from the skin like a brick, and had that ugly, gigantic white football-shaped adhesive (imperfectly applied; hence the wrinkle) surrounding it. And this is with the newer, slimmer transmitter! Turns out, the “sensor pod” that it snaps into adds plenty of bulk itself.

Compare this to the Medtronic transmitter which sits off to the side.  After my Enlite sensor expired, I tried to tape it next to this one just to illustrate the comparison. The tape-job is awful, but the Enlite is noticeably much flatter.

Dex vs Enlite

I had been in close contact with (No More Shots For) Shannon during this process, since she was just beginning a week-long trial of the G4 at the same time. She had just inadvertently knocked her sensor off around the same time I put mine on, so I didn’t have a good feeling about this oversized CGM. I’ve heard of this happening before, and it only happened to me once in four years with the MedT system.

It was easy to insert, though. And I could see how it can be done one-handed on “alternate” sites; something that is quite difficult with the Enlite.  In the end, the size difference is a trade-off of one dimension for another. The larger surface-area of the Enlite causes problems as the body moves and the skin twists and stretches, yet the height of the Dexcom makes it more delicate and prone to damage.

And one more thing — after getting an hour of ???’s on my Dexcom screen following my shower for the next two days, I discovered that the transmitter wasn’t fully snapped into place. I guess the self-training wasn’t as effective as I had thought. But after I snapped it in (hoping no moisture was trapped in there), I was back in business in about half an hour.

Verdict: undecided.


May 2014 prediction on Receiver: “Extra device to carry around — carefully, or the buttons fall off.”
May 2014 prediction on Graph:”High-res, easy to read. Not a fan of using “red” for high, as the color incites rage on top of the inherent high-BG frustration. Three levels of trend-up arrows and three levels of trend-down arrows.”

I wasn’t sure how I’d feel about carrying an extra device around. But I find that at work and in the car, I kinda prefer it. It’s small and light enough to slip into a shirt pocket, and I can easily access it (or set the receiver on my desk) without fiddling around with the pump clipped near a more private part of my body. When I found myself refereeing my son’s soccer game over the weekend (because the ref never showed up), I used the included belt-pouch clipped to my belt. The way it opens up, orienting the display in a manner suitable for looking down at it, was nice. But the pouch was very tight, and I suspect it’s responsible for so many of those those USB-port covers popping off.

The display is, without a doubt, magnificent. I didn’t think I’d much care about it, but it’s really nice and pleasing to the eye. I can now see myself letting the display factor into my choice of D-devices. I was mistaken, though, when I said last year that the red color was used for a high. In fact, it’s used for a low, but I still don’t like it. Red-on-black is difficult to read — and it still incites a Holy-shit-I’m-gonna-die-gotta-do-something-NOW! response, which I don’t like. Especially since, without predictive alerts (more on that later), the threshold is set where I want to know about it, not where I’m really in trouble.

I miss the ability to scroll-back to see prior BGs.  The trend-arrows give an idea of what’s going on, but I used to like to look back 5 or 10 minutes to assess for myself which way I’m trending and at what rate. Perhaps over time I’ll grow to understand and trust them, but not yet. And the horizontal (east) arrow is misleading, because there is ALWAYS a subtle rise or fall with my BG. Always.

Verdict: pleasantly surprised.


May 2014 prediction: “Only one high- and one low-threshold. No predictive alerts. Dex-in-a-glass workaround.”

First things first; I have my Dexcom receiver set for audible alerts (“Attentive”, to be exact.)  Never in my wildest dreams did I expect to do that — but there are enough vibrating alerts that precede the audible alert, in any profile, that I’m comfortable doing so. The vibrating alert is stronger than expected, with different patterns (which I’m still learning) for different alerts, and the audible alert is plenty loud for me.

Clearing the alerts is easy. Just press the center Select button. Since the receiver is a CGM only, it always works. I did catch myself once pressing Select-Right, to mimic the ESC-ACT sequence of the Medtronic. (Also, the Medtronic sequence is awkward; sometimes the alert doesn’t clear on the first shot — it depends what’s shown on the screen at the time.)

But that’s where the pleasantries end.

This is what a low alert looks like: (that white rectangle in the top corner is actual a gray area with some white trend-line dots that just didn’t come out in the photo).

LOW alert

That is what EVERY low alert looks like.  Whether my sensor glucose level is 85 or 65.  It shows the threshold limit, not the actual sensed glucose level, and an icon of a trend-line that seems to be flattening out.  A high alert is similar. It shows a giant 165 mg/dl (which is my set threshold), even if my sensed glucose level is really 265.

If I was 85 and my trend-line was flattening out, and perhaps making an upward tick, I’d be comfortable.  But this was the reality of the situation at that time:

LOW graph

Quite a different story, and quite a different response.

I appreciate the gigantic number in the alert, but for God’s sake, why can’t the number be correct!?!

But that’s not my biggest complaint about the alerts.

The beauty of the Medtronic CGM system is that there were NO SURPRISES. I was never caught off-guard by a high or low glucose reading, because I had a “Predicted Low” or “Predicted High” alert that preceded it. I’d also gotten in the habit of acting on those predicted alerts, in hopes that the actual BG-excursion wouldn’t go too far. But with the Dexcom, I’ve had plenty of surprises. I’ve found myself, more times than before, frustratingly trying to recover from an out-of-range BG than avoiding one.

I’ve tried playing with the settings, moving the thresholds tighter so that I get alerts earlier. Adjusting the “Snooze” settings (which will re-alert if the BG is still out of range) to be more frequent. Tweaking the Rise-Rate and Fall-Rate settings (which only have two settings, by the way: 2 mg/dL/min or 3 mg/dl/min). But I just don’t think I can make up for the loss of predicted alerts. But I’ve got time left in my trial, so I’m going to try…

Verdict: I can honestly see the absence of a Predictive Alert leading to my A1C rising or to more severe low BGs. We’re not talking convenience or niceties anymore. This could very well prove to be a reason for me to want to switch back to the Medtronic system.


Next time… I’ll share my observations on accuracy, data reporting, landfill-contribution, and trustworthiness.


I have no recollection of that bolus, Senator

I woke up low yesterday morning.

Which, ordinarily, is no big deal. It happens. I’ve been pretty aggressive with my pre-dawn basal rates, actually trying to program a Super Bolus into my regular basal pattern (jack up my basal rate really high one hour, then cut it down to almost zero for the next) so I wouldn’t need to play those games every day at breakfast.  That hasn’t been working too well, but that’s not why I woke up low.

This is why I woke up low.


Apparently, for reasons I can’t remember, I decided to give myself a shit-ton worth of insulin at 3:25 in the morning. Without entering a BG. Without entering carbs. Just straight, unjustifiable Novolog.

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The Big Chill

Ironically, the low-point of my CGM graph makes it look like a big smile *

Ironically, the low-point of my CGM graph makes it look like a big smile *

I am guilty of a scary borderline-serious low this evening.

I say borderline-serious because I was still fully aware of what was happening around me, and because I never reached that confusing haze, also known as Telltale Sign Number One.

I say borderline-serious because my CGM was, at one point, showing a 54 mg/dl with double-down arrows.

I say scary because I felt fine – I had no idea I was so low (and going lower, with a full unit of insulin on-board from an earlier high correction). I would not have known if not for my CGM alert, and even then, I thought it was a false reading until my meter confirmed it.

Then the sweat caused my shirt to stick to my back, and my hand to constantly wipe my oversized (thanks, receding hairline) forehead. Then I really believed it.

Though I’ve been doing a really good job of keeping by blood sugars on the lower-but-normal side in the eight weeks or so leading up to Thanksgiving (I’m targeting a monumental A1c improvement), I’ve pretty much fallen off the wagon since Thanksgiving, so much to the point that I’m feeling lows when they aren’t really low, which has led me to trust my feelings more.

Sometimes, trusting one’s feelings is a good thing. When it comes to hypoglycemia awareness, it is not

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How to build a better Enlite

A little over a year ago, I wrote a post on How to build a better insulin pump, based on the Medtronic Revel. Since very little has changed from the Revel to the 530G, those wishes/recommendations still apply. But now that I’ve had some time to play around with Enlite, I’ve got some wishes/recommendations on how that can be improved upon as well. My reason for posting this is simple — if nobody knows, nothing will change; but if someone (or some-two, or some-many) makes noise, it’s more likely to be heard. With the goal of being taken seriously, I’m keeping my recommendations somewhat simple and realistic.

* * *

The new Enlite and Enlite “Serter” are a vast improvement over the predecessor. In nearly every way. That goes without saying.

When I first saw the Sofsensor, I concluded that this must have been designed in-house by Medtronic, and not by Unomedical, the Masters (and manufacturer)-of-all-things Infusion Set related (and whose website appears to be out-of-commission at the moment).  Medtronic’s first CGM lacked the characteristics of something being designed by the Masters.

Enter Enlite. It’s better, and it took into account all the feedback received from Sofsensor users. It, too, has been designed in-house. And  sadly, it too lacks some of the characteristics of something designed by the Masters.

Let me be clear: I do think the Enlite is a good product, and this in no way is meant to be criticism worthy of driving someone away from using it. My reason for writing it is so that Medtronic – or perhaps another manufacturer – can learn something and make improvements the next time around. My hope is that they’ll take a look at some of the “little things” that can leave a big impression. And maybe, just maybe, the current product can undergo minor improvements while still being the current product.

Allow me to explain.

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A weighty decision

Dx-on-dischargeWhen I was first diagnosed with diabetes, I took one insulin injection a day: a little bit of Regular and a little bit of NPH mixed in a syringe before breakfast. That quickly shifted to twice a day: before breakfast and before dinner.

I had a glucose test kit that stayed in the school nurse’s office. In 1981 (1st grade, diagnosis), it was a urine test, in 1991 (11th-12th grade) it was a blood test. But it was there, not with me.

The only thing I carried around with me everywhere I went was a little box of Sun-Maid raisins, in case I felt low. Or maybe a roll of Life Savers, which always ended up permanently stuck to the paper wrapping (and each other) ensuring I had plenty of fiber with my low BG treatment.

At some point I switched to blood tests, first by holding the strip up to a  color chart, and later by using a big, clunky meter. I took it with me on family outings, but I don’t remember ever taking it to school. All I took was the box of stale raisins to treat lows; or maybe a roll of Life-Savers, inseparably stuck to the foil wrapping and each other.

I don’t ever remember carrying a meter with me in school. In 9th grade, I had a late lunch period and consistently went low during my biology lab period before. But I fought through it like a champ chump, traveling light.

I can’t remember if I carried a meter with me to class in college. Twelve years later after diagnosis, I was still on just two injections a day, each was a mix of Regular and NPH, taken before breakfast and dinner, with the Regular dose on a sliding scale that increased with my blood sugar. The scale matched the intervals on the old Chemstrip color chart: 180-240, add 1 unit. 240-300, add 2 units. 300-400, add 3 units, and so on.

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