LifeAfterDx--Diabetes Uncensored

A internet journal from one of the first T1 Diabetics to use continuous glucose monitoring. Copyright 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016

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Location: New Mexico, United States

Hi! I’m William “Lee” Dubois (called either Wil or Lee, depending what part of the internet you’re on). I’m a diabetes columnist and the author of four books about diabetes that have collectively won 16 national and international book awards. (Hey, if you can’t brag about yourself on your own blog, where can you??) I have the great good fortune to pen the edgy Dear Abby-style advice column every Saturday at Diabetes Mine; write the Diabetes Simplified column for dLife; and am one of the ShareCare diabetes experts. My work also appears in Diabetic Living and Diabetes Self-Management magazines. In addition to writing, I’ve spent the last half-dozen years running the diabetes education program for a rural non-profit clinic in the mountains of New Mexico. Don’t worry, I’ll get some rest after the cure. LifeAfterDx is my personal home base, where I get to say what and how I feel about diabetes and… you know… life, free from the red pens of editors (all of whom I adore, of course!).

Thursday, November 08, 2007

Fiddlesticks, a morning of many fingersticks

I put the last sensor in the box into my leg this morning. It went in with no trouble. No pain. No blood. A pleasant change from recent experiences.

Ten minutes later I get a sensor error. Then a second. Then it shut down.


I carefully pealed off the IV 3000 dressing, unplugged the transmitter, and plugged it back in.

Of course I already have the next box of sensors. I keep one box ahead. MedT’s recent supply problems make life terrifying for the sensor dependent like myself. Back orders on sensors are running upwards of three weeks for current users and 6 to 8 weeks for new starts.

I guessing MedT is having some issues up-scaling their production. But, so far, I’ve only had one batch that didn’t run as well as I expect. I’m hoping that MedT doesn’t become the victim of their own success. I got to visit the original manufacturing site quite a while back. At that time the damn things were pretty much made by hand one at a time. It gave me new respect for the then $45 each price tag. Automating that process, I sure, has turned out to be a huge challenge.

After I re-plugged in the transmitter, I kept an eye on the ISIG, which you find in the Sensor Status menu. The ISIG is the raw signal coming off of the sensor. Mainly the NoHelp Line uses it, the manual doesn’t shed much light on it, but I can tell you a few useful things that I’ve learned about it over the years.

The system takes the raw signal and, using the magic of math, compares it to your calibration sticks, applies a bunch of fancy priority algorithms, and translates it to a SG number that you and I can understand. I can’t remember the exact number (should have written it down) but I think if you multiply the ISIG by 8 you get the approximant blood sugar. But don’t bother. There are a number of reasons this doesn’t always work.

When you first plug in a sensor, during the warm up period while it is settling in, you’ll see 250+ ISIG numbers. Of course your blood sugar isn’t really 2,000 BGL. That would be fatal either from the sugar or the heart attack you’d have when you were told that’s what your sugar is. By the time she’s ready to go the ISIG is commonly in the 15-25 range.

All you really need to know is that if the ISIG is in that range you’ve got a pretty good sensor set. In time the signal will degrade. The human body is an extraordinary hostile environment for foreign objects like sensors. I find that the monitor can compensate for ISIGs down to 8 or 9. After that, you’re gonna get a CAL ERROR. The signal has gotten so weak that the system can’t reconcile the data being transmitted with the blood glucose number you are trying to feed it. At that point it is end of the road for the particular sensor.

If a new sensor is running below 10 ISIG, you’ve got a bad set. Maybe it got bent going in. Maybe it got hit by cosmic rays. Maybe….

Guardian sensors are FDA approved for three day wear. Many users wear them for longer periods. I won’t say what I do. You gotta find your own way. I know of many people who wear the sensors 6 days to a week. I heard of a guy who wore one fourteen days. I don’t think I’d want something “in” me for that long. Infection risk goes up with each day. I’d also think that in most folks the signal strength would be pretty weak by then. Oh well, your mileage may vary.

I kept an eye on the ISIG. It was running 55.75 Then it dropped to 4.32 Then jumped to 42.88, then back down to 5.33. This is very strange. It should start high and gently settle down. Something is wrong with this sensor. Meanwhile, in the ocean with out my life jacket, I’m doing fingersticks every 15 minutes during this prolonged period of no CGM coverage.

No CGM. Worse than leaving the house without your cell phone. I feel totally naked. And not like the having fun kind of totally naked. More like those nightmares well all had in third grade, you’re giving a book report in front of the entire class, when all the sudden you realize you forgot to put clothes on before you came to school. Then you wake up in a cold sweat. So hence forth we could say cold-sweat naked and you’d know we were not talking about the good kind of naked.

I fought with cal errors, sensor errors, and shifting sands on when I’d be allowed to actually try and get the first cal stick in for eight hours. It was clear this sensor was not going to work.

Damn! May the fleas of a thousand camels infest the arm pits of the person responsible for this piece of crap! No, wait a sec. Might be my fault. Best to be careful with your curses. A highly placed researcher once told me that ALL sensors functioned perfectly in the lab. It was just in that annoying human body that they had trouble. He seemed insulted that his perfect sensors had to go into us. Hmmmmm….I’m thinking he’s missing the point on the purpose of his creation…Well, brilliant folks don’t usually have both feet on the ground, after all.

With extreme disgust and a sense of longing for the twenty-dollar bill the sensor set me back, I peeled the tape off and pulled the sensor out of my leg. Ahhhh…the things I could have done with that twenty. I could have taken the family out for a simple meal. I could have bought a pipe on EBay, or a couple pairs of interesting ear rings. Or ten cups of Starbucks coffee. A small drop of blackish-red blood oozed out of the hole. The sensor wasn’t bent or kinked in anyway. I stared at it’s dull gold glow, but nothing seemed out of the ordinary.

Well, in the greater scheme of things, there are more important things to worry about. I put in a second sensor. And got a sensor error. After taking five blood pressure pills I went on with my day.

The senor ran “hot” during it’s entire warm up period. When it signaled it’s willingness to be calibrated it was above 35. Very strange. Right after calibrating the SG curve shot up, gave me a high alarm, and kept climbing. That’s odd. I haven’t eaten much….

Fingerstick. Wasting a lot of strips today for a guy with CGM. Guardian has me at 245. I’m at 150. The ISIG is still raging like a bonfire. I’ve never had this happen to me before. I consider feeding the unit a few more fingersticks to reign it in, but the worst thing you can do is over-calibrate, and the stupid machine still thinks I’m on a rise. If I give it sticks while it’s in “motion” I’m asking for trouble. I need to be stable, it needs to be stable. That gives time for all the math to happen. Having just pissed away twenty bucks, I’m not to keen on double or nothing. I decide to keep pissing away test strips instead, hoping the site will settle down.

First days are often the worst when it comes to sensor performance. The key is not to stress out in the first day. I think several things happen after the first day. After the first day the sensor has a greater “bank” of calibrations to really on, and I think your body settles down around the sensor in a good way. After all, you’ve torn thousands of cells asunder putting that monster needle in.

At bed time I needed to give it a fingerstick, as I didn’t want her waking me up at 3a.m. My BG was fine, but she didn’t think so. The two numbers were over 150 points apart. I knew what was going to happen next.

Sure enough. CAL ERROR. I trudged, dejected into the library, where Deb has discovered the internet (you know what I mean). This isn’t going well babe.

“Hmmmmmmmmmm?” distracted, looking for the near impossible to find CD musical sound track of Rome Adventure, apparently only released in Japan a few years ago. She’s not looking for a DVD of the movie, but just a CD of the music from it. If you know where to get one, let me know.

I tell her I’m anticipating another CAL ERROR. I had a light dinner, no desert. My BG is stable and there is little or no Humalog fast-acting insulin “on board” (meaning in my blood stream). There is a forest service sign near the clinic. Smokey Bear holds a sign, Fire Danger Today: X. And every morning some poor ranger has to change the sign. The fire danger varies from Low to Medium to High to Extremely High. Hypo Danger Tonight: Low. Thanks Smokey.

If the thing craps out on me, I’m going to turn off the monitor but leave the sensor and transmitter in place over night. Maybe it will settle down and work right tomorrow.

She doesn’t hear me. The magnetic field from the computer no doubt interfering with her hearing.

I feed the fingerstick to the Guardian and tuck my feet under the three blankets I have on my bed to fend off the night cold (hey, it’s a desert, but we are right at a mile above sea level in my living room). I get my head adjusted right with two pillows so I can read for the fifteen minutes it will take to either calibrate or fail. I pick up the Flinders Petrie bio and take up where I left off. The year is 1890 and Flinders and I have just returned from a miserable season in Palestine and we are sure glad to be back in Egypt where the workers aren’t so lazy and we are more accustomed to the culture. I really do get into a good book!

Absorbed by the artifacts we are digging up, time slips past me and after a half an hour my eyelids are drooping. I gotta start getting more than six hours of sleep each night!

But there has been no calibration error. I put the book on top of the three-foot stack of books by my bed side, set my glasses on top, and turn off the light.

The dawn is cold. It is 66 degrees in my bed room, according to my HoMedics indoor/outdoor thermometer, alarm clock, and white noise machine. I do my dawn fingerstick. Within ten points of Guardian. Now that’s more like it. I check the ISIG and find it still running hot and high at 36.68, very strange.

But the algorithms are in harmony once again and Guardian is giving me an accurate picture of the dance between my defective endocrine system and my blood sugar. Today far fewer tests tips will be sacrificed on diabetes’ altar.


Blogger Caro said...

It's strange when you don't get the Cal Error you're expecting.

I don't normally even bother to give my 522 a number that is way off whack with what it already has, becase two Cal Errors inevitably follow. I've tried it enough times to not go there. (What I do instead is a different story!)

A couple of weeks back I had a similar experience to this. The ISIG was running high and so were the CGM numbers. It was trending ok though and running at a consistent level above where I really was. Until, that is, whilst I was at the cinema, it suddenly shot up. Five minutes later it asked for a calibration. I was watching a film, didn't really want to think about it, so I just plugged in the real number and waited for the Cal Error, which came. I then stuck in the number again. The plan was to get it to go to 'Bad Sensor'. It could then wait in abeyance without bugging me until I was done with the film.* I was completely shocked when the end of the film came and I realised it had just flipped back on track, despite the ISIG staying high.

*The reason I do it this way is if you switch the sensor off or disconnect the transmitter, you have to go through 2-hour restart when you're ready to tackle it. 'Bad Sensor' can be restarted in the same way as a sensor restart at the 3-day 'Sensor End' i.e. Start Sensor --> New Sensor, then Enter Meter BG (you don't have to wait for the prompt, it will take it anyway). If the sensor comes back on track, which they frequently seem to after a brief break, you get going again in less than 15 minutes.

11:20 AM  
Blogger Bernard said...


When this stuff works it's just great. And when it doesn't it's hard to describe the angst and anguish that it causes.

But you've done a good job at it.

May all your future sensors calibrate with ease. (It's an old Irish blessing).

11:23 AM  
Blogger josl said...

This comment has been removed by the author.

1:42 AM  
Blogger josl said...

hang in there...nothing more frustrating than a late night with malfunctioning BS levels or equipment....

1:49 AM  

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