Adverse pump event, or the ultimate in bad fucking luck?
Extra! Extra! Breaking news! Man survives killer low in the night! Read all about it!
You know that built-in fixed alarm on the Dexcom G4? The one the manual talks about? The one that you can’t turn off? The one that goes off at 55 mg/dL? I got to hear it last night.
It goes Bzzt! Bzzt! Bzzt! Rapid. Staccato. Three times in a row. Bam-Bam-Bam. Un-comfortingly like machine gun fire.
I know this because last night, well… technically this morning, I had my worst hypo ever. Not the lowest; but the longest. I spent an increasingly terrifying total of 1 hour and 25 minutes in the hypo range—below 75—and a whopping 40 minutes sub-50. And nothing I did, nothing, would reverse the trend. It was like being glued to the train tracks with industrial-strength epoxy while watching the express barreling towards you.
My Dex4 fast-acting glucose was like water. My glucose tablets were no more than celery sticks. And shortly before the ice broke, my addled brain entertained a horrifying thought: Maybe my new pump is malfunctioning. Maybe, even though I suspended it almost an hour and a half ago—maybe—even though every indication on its control panel is that it’s dormant—maybe—it’s still throwing fuel on the fire. Maybe it’s pumping away like mad, feeding the never-ending low.
Here’s how it all went down:
12:13 a.m.—A low threshold alarm on my Dex G4, set at the factory default of 80mg/dL, goes off. I groan, swear, and mutter under my breath. After cancelling the alarm, I feel for Mr. Pump’s infusion set tubing in the dark, and finding it, reel the pump in. It’s hiding somewhere in the covers. I wake up the pump and enter a Temp Rate of Zero for 15 minutes, and drink about half the bottle of Lemon Lime Liquid Blast glucose fluid from the just-for-in-case bottle that lives on my night stand.
I use Temp Rates to suspend the pump when I’m low, so I won’t have to worry about un-suspending later, or being pestered by the “Hey, did you know I’m turned off???” alarms that Mr. Pump gives me if I use the Suspend feature instead.
This is my default approach to nocturnal lows. I’m not overly concerned. There was no drop-rate alarm, so this is a slow-moving emergency. Dinner was hours ago and I didn’t need to take a correction at bedtime. There’s nothing but basal on board. Perhaps I’ll need to tweak it in a day or two. Or not, I was a bit more physically active yesterday, I could be paying the price for it now.
12:26 a.m.—Two minutes before my temp rate expires, and 13 minutes after drinking the glucose, my blood sugar has dropped to 67. Not good. I cancel the Temp Rate and enter a longer one: an hour and a half. I drink the rest of the glucose liquid.
12:43 a.m.—The fixed alarm goes off. I’m now at a sensor glucose of 55 mg/dL. Things are very quickly spiraling out of control. Dropping that much? That quickly? After drinking glucose fluid? Could the CGM be freaking out? A fingerstick confirms the damn sensor is right on the money. Dexcom weren’t lying when they said the new G4 sensors have stellar performance in the low range. I start munching glucose tabs.
12:48 a.m.—Sensor glucose dips into the 40s. This is crazy. I haven’t seen a real 40 since… since… since I don’t know when. My CGMs have never let me get this low.
01:03 a.m.—Sensor glucose bottoms out at 44 mg/dL.
01:08 a.m.—Sensor glucose is still at 44 mg/dL. A fingerstick confirms this is the real deal. Seeing the face of my Dexcom receiver glowing blood-red in the dark of the night is un-nerving. A long row of bright red dots march across the screen. Bzzt! Bzzt! Bzzt! My G4 receiver looks like the bullet-riddled body of a Mob hit.
01:13 a.m.—Sensor glucose is still at 44 mg/dL.
01:18 a.m.—Sensor glucose rises to 49 mg/dL. Relief sets in.
01:23 a.m.—Sensor glucose drops again to 48 mg/dL. Panic sets in.
But then, as the “maybes” about the pump fill my brain, and just as I was fixing to rip the infusion set from my body and toss the fucking pump out the window, the ice broke. My blood sugar rose from 48 to 56. Then five minutes later from 56 to 67. Then to 80. Then to 91.
It was over. I set a final Temp Rate for another hour and a half and succumbed to restless sleep, full of fitful dreams dominated by machine gun fire, equipment failure, crashing planes, runaway trains, glowing pools of deep red blood, and big-busted Angels of Death in black lacy lingerie (always male to the last).
This morning I woke unsure who to call: Tandem? The FDA? Bernard? (Seriously, he’s the closest thing we have to the Ghost Busters when it comes to D-Tech.)
But, in the pale morning light of a new day, like a NTSB crash investigator, the fact that the airliner went down is incidental to me. I just want to know why the fucker crashed. Because this was no ordinary crash. It acted like a serious insulin overdose. I needed to know if I had just suffered a genuine adverse pump event.
After all, t:Slim is still new to the market. What if it had some sort of glitch? What if some other type 1 out there had the same thing happen? What if that person didn’t have CGM? A low that long, that deep, that persistent—even with a boatload of sugar thrown at it… What would have happened to a sleeping beauty with no alerts, no chance to throw glucose tablets into the gaping maw of the low? I have no doubt whatsoever that the answer would have been: Seizure. Coma. Angel of Death. No lacy lingerie included: Just paramedics and tears by dawn’s early light. Dead in Bed.
For this crash investigation, we have the plane’s three black boxes. Black box number one is the Dexcom, G4. The hero of today’s story. Sadly, the device itself has no alarm history. More sadly, the Dexcom studio software, for all its lights bells, and whistles, doesn’t have an alarm history either. But with the software, a pen, some paper, a calculator, and with one hell of a lot of work, we can learn quite a bit.
Black box number two, the possible villain in our story, is the Tandem t:slim. Sadly, again, black box number two has no software (yet) so we can only look at the delivery logs on the device itself.
Black box number three, is my meter, which can only serve to confirm that black box number one was reporting the flight data correctly, which is was. By the way, you do know that real “black boxes” are orange, right?
Oh, plus for our investigation, we have the testimony of the sole survivor (thankfully). But this is our least reliable source of information, as my brain is probably damaged by the hour-and-25-minute-long low. Plus my brain wasn’t that great in the first place. Plus my brain has no written logs nor software that allows me to download it. A mixed blessing, surely.
In the bright light of day in my library, on my computer screen, the low didn’t look so bad as it did last night when the receiver bathed me in red light. The low coasted onto the scene. A slow steady drop from my after dinner peak of 158 mg/dL at 8:03 p.m. It doesn’t look dangerous. But, damn, once it got low, it stayed low for a loooooooooooong time despite all waking efforts to reverse it.
The pump didn’t shed much light on the crash, other than confirm, at least according to the history logs, that I didn’t do something stupid like bolus rather than suspend in the middle of the night. But it did give me the first clues as to what might have caused the crash of Flight 44, at least by ruling out some possibilities. Dinner was at 6:50 p.m. That means, as I thought in the night, the insulin from dinner was long gone by the time the shit first hit the fan at 12:13 in the morning. The dinner bolus would have run its course by 9:50 p.m., fully two hours and twenty-three minutes before the plane hit the first mountain peak on its flaming decent. And it wasn’t even an overly large bolus in the first place. 1.59 units to cover a 22 gram meal with a correction for a pre-meal BGL of 160 mg/dL. And it was a “perfect” bolus, 4 hours after the meal, the blood sugar was 120, only 10 points above target. The meal was covered, the blood sugar was “fixed.” Damn I’m good.
Or maybe not.
Because the Dex download shows a different story playing out. Starting out about 10:30 p.m. the sensor glucose starts to drift steadily downwards. Too much basal insulin is indicated. But if that’s true, I should have been having lows many nights in a row. I haven’t touched the basal rates in a week or more.
So I looked back, and sure enough, the same steady downward drop shows up on many a night over the last week. Crap! My blood sugars have just been such a mess this week they never got low enough to make an impact. I missed it. Shit!
I had seen some gentle downwards trend on the CGM traces overnight in the wee hours, so I’d been fucking with my post-witching hour basal rates. After midnight it drops to 0.8 units per hour. At three AM, even lower. But I totally missed the possibility that the problem might be coming from earlier in the evening where I’ve been running a stronger 1.0 units per hour. The trees of basal were lost in the forest of dinner and correction boli.
And this is also an example of how our tools screw us. The midnight-to-midnight software for the Dex G4 gives you a poor snap-shot of how we really live our lives. A much more useful graph would be to display my CGM traces on 6 a.m. to 6 a.m. overlay to look for trends. Let me see my 24-hour life the way I live it. Let me see my night for what it is: one night. Not two nights, the back-half on the left side of the screen; the front-half on the right side of the screen.
But still, I’m not 100% satisfied that the low was triggered by too much basal in the hours leading up to midnight. First, I’ve been running that level of basal at that time of day since I started the pump right after Christmas. If I’m running a lot more than I need, I should have had trouble before now. And I’m still befuddled by the sheer tenacity of last night’s low. I think my basal rates are pretty low for my size. The first shot of glucose should have sucked up the extra insulin lickity-split.
And no, Uncle Wil wasn’t drinking too much, either. I actually drank much less last night than I usually do (further proof that no good deed goes unpunished). I had one glass of wine, rather than my normal two, with dinner, as we had just run out. The economy and all. Plus, I’m having a hard time shedding that five pounds from the holidays, and the extra calories in the carb-free wine probably aren’t helping.
I was a little more active than usual, but not by much. Some minor household repair stuff. Not exactly a major work out.
And consider this: according to the pump log I had no insulin between 12:13 a.m. and 2:30 a.m. That’s two hours and 17 minutes with no life support. Plus I consumed a ton of glucose. Considering all of that, I should have had a hell of a rebound excursion. Where do you suppose I woke up when the alarm went off at 5:30? At only 170 mg/dL. I expected it to be much higher. Sure, it’s not exactly on target, but not the 250-300 I probably deserved, or have seen in the past.
So just to be sure Mr. Pump was telling the truth I suspended him via a Temp Rate for half an hour this morning, leaving the tip of the infusion set on top of my iPod Touch’s screen. Nary a drip nor drop nor smear of insulin was seen. It didn’t even fog the mirror-like glass surface. No insulin escaped from Mr. Pump while the Temp Rate ran.
So what was the cause of the crash? Engine failure, or pilot error? I don’t know. But I decided that I had to call Tandem. It might have just been my basal having an unexpectedly powerful effect on my body. Or maybe I got defective glucose. But… well, if something did happen with the pump, the next person it happened to might not be so lucky. I picked up the phone.
I spent about 45 minutes or an hour with their tech people, who frankly had a hard time getting their heads around the problem. I was lectured about leaving my cartridge on beyond the FDA indicated three day wear-time. Guilty as charged. But if that had bit me in the butt, I should have gone high, not low. Same with infusion set issues, although the tech support lady did ask if I put the site on a very different part of my body. I didn’t, but that was good thinking. Some areas absorb better than others.
I thought I was on to something for a minute when I realized that the “fuel gauge” on the pump showed about forty units less insulin than I thought it should given the amount pumped, plus the amount in the tubing, since the last change—but it turned out to be an illusion. An artifact of how the pump detects and reports insulin.
At long last the Tandem lady decreed she couldn’t seem to find anything wrong with the pump over the phone, told me they have no way to get any more info out of it than I can read on the pump itself, and said, “All I can suggest is you continue to monitor it.”
Oh, and if I have any “further incidents,” we “may” consider replacing the pump.
I didn’t know how to respond to that. So I didn’t. The silence grew uncomfortable until she finally asked me if I was OK with that. I can’t recall if she said it flat out, or beat around the bush, but I got the impression they’d replace Mr. Pump if I made a big enough stink. But really, even I confess this is a mystery. This isn’t like the Med-T pumps, regurgitating error messages all over the place. The pump gives every sign of working correctly. I can’t really see a reason they should replace it.
It’s a blood sugar mystery more than a pump mystery. Granted, a blood sugar mystery that acts all the world like an insulin overdose, but there’s no evidence beyond one crazy stubborn low that it was.
“Are you comfortable wearing it?” she asked.
Are you diabetic? Was my reply. No. Her family is chock-full of dFolk, even including her cat. But not her. Well, there’s still time to join us, I gently teased her. I could practically hear her crossing herself. It’s hard to explain how scary this is, I told her, I’ve never had a low this bad, this stubborn before.
But in reality, I survived with no seizure. No coma. And the big-busted Angels of Death in black lacy lingerie didn’t drop in for a visit, or even a brief cup of tea. I told her that I really just called to make sure they were aware of the possible problem. Just in case. Just in case I wasn’t the only one. If this had been a pump problem, I told her, and it had happened to someone without CGM, it could have been fatal. This was serious.
“I know,” she told me. “If you had called us where you were last night, we would have called 911.”
Again, I didn’t know how to respond to that. My sugar was so low it never occurred to me to ask for help last night. After another pause she said, “Well, if it happens again, we’ll replace the pump.”
If this happens again, you couldn’t pay me enough to wear your damn pump anymore, I thought to myself. But I thanked her for her time and her kindness.
I guess I’ll never know why the hypo was so wicked, so deep, and so stubborn. I guess it was just one of those things. Still. It’s a scary reminder of what a difficult game we are players in. Diabetes is a dangerous businesses.
So now what? I reduced the evening basal rate. I took a correction for my morning high and Mr. Pump fixed it just fine. Right now, all systems seem to be go. Right now, I’m at 105 mg/dL, level and stable.
Right now, I’ve still got Mr. Pump in my pocket, steering the ship on calm seas. But of course, my wife hasn’t read this post yet, either.