Please Do Not Remove My Batteries


Minimed MiniLink TransmitterAs of Saturday, March 6, at 10:40 AM, I am one step closer to having my robot pancreas.

I have, through a combination of landing the best endocrinologist in the Kaiser system and being a persistently squeaky wheel, gotten my Medtronic Minimed Continuous Glucose Monitoring System. I am phenomenally excited about this development, and not only because I get to imagine myself as a sexy anime cyborg: I love data, and my heart beats with a quick rhythm at the thought that I will soon be able to improve my diabetes care, and resultantly the quality of my daily life, with the help of more data and more data analysis. With this CGM, I hope to get a better picture of where I stand, and with that I hope to build a better system for getting me where I need to be.

So, some notes from setting up my newest biogadget:

Getting the goods

Just in case you had any doubts that medical devices were a high margin product, know that I received several calls from several different Minimed representatives, each of which went over some aspect of the delivery, pricing, billing, or training that would be scheduled. The Medtronic box arrived via 2-day UPS shipping on Friday evening, with a trainer due to call me the following week.

Minimed Transmitter or Klingon weapon?When I opened the box, my first thought was that perhaps they had accidentally delivered some sort of Klingon weapon. I quickly realized, though, that the oddly shaped, spring-loaded device was the assistive inserter for injecting the sensor into my abdomen. The insulin pump comes with a similar device. I hate that thing. The mere thought of a spring-loaded, large-bore needle pointed at my stomach makes my cringe.

After investigating the various components (Klingon injector, little blue thing, bigger blue thing, small white flying saucer), I pulled out the instructions. While I had no intention of waiting to receive training, I did at least intend on reading the instructions.

Step 1: Charge your new MiniLink REAL-Time Transmitter.

Takes up to eight hours to charge the first time? Really? Lame! I was to ready to get going! Luckily, the actual charging time was only 15 minutes, a far cry from the threatened eight hours. I was pleasantly surprised.

Step 2 through One Million: Read each and every one of the many brightly colored instruction booklets included in this box, plus anything Minimed has ever sent you, ever. Oh, and:

DO NOT insert a glucose sensor or use your MiniLink Transmitter until you have attended training.

Yeah, right. Moving along, I identified the pieces I needed (box of sensors, transmitter), and tried to figure out how to get the thing on me. Unfortunately, the instructions only showed how to do it with the evil spring-loaded needle-shooter. So I was on my own.

Minimed Sensor InserterI opened one of the sensor packages. Wow. That is one big needle. I use the Minimed Silhouette infusion sets, which are pretty big themselves, but this guy was thick. And the angle was more severe than the Silhouettes, which made me think queasily about where the tip was going to land inside of me. And the sensor itself looks like a giant mosquito. Yikes.

It took me about three tries to finally get the sensor inserted. The first two tries I got the tip in, and then bailed as my fingers began to slip and I couldn’t seem to get sufficient tension to push through the elastic skin into the interstitial fluid. Once the sensor was in, though, I realized I didn’t know how to remove the needle part to leave only the sensor behind. In all the provided instructions, the injector seems to take out the needle automatically, so there was no indication of how to do it by hand. I pulled a little, but nothing happened. So there I was, half naked, beginning to panic because I had a large, sharp object hanging out of my abdomen. Breathe. It’s got to be just like the pump infusion set, right? The plastic part disconnects, and the needle can be extracted. I pulled harder, and felt the plastic inserter begin to disconnect, pulling the needle back with it. Sigh of relief.

Watching the Pot Not Boil

That was just the beginning, though. Next came the waiting. Ten minutes of letting the sensor get “wet with interstitial fluid.” (Ew. Way to word that one, Minimed.) Then FOUR HOURS before the sensor began to actually tell me anything. Four hours of startup time! Now, in retrospect, that doesn’t seem so bad, especially considering I had no continuous sensor before. But still! During that four hours, I checked the thing every ten minutes, and it wouldn’t tell me anything. Which leads me to an important note for Minimed developers, medical device designers, and anyone who designs a user interface for anything, anywhere: if the user is waiting for something, show the user a visual indicator that something is happening. A loading bar. “Waiting for data.” An hourglass. The Mac spinny beachball. Anything! Tell me something is happening! All that the pump said was “Sensor Start,” so I was unsure if that meant “It’s in the start-up phase,” “It has been started,” or “You did it wrong; start the sensor again.” I do not like waiting, unsure of whether I should restart the whole process.

The Payoff

Minimed Sensor ReadingBut then. Finally. I start getting data. Blood glucose measurements! Every five minutes! If you are not a diabetic or not a geek, this may not mean much to you. To me, this is awesome. Yes, literally– awe inspiring. This will make my life so much easier.

And one weekend in, it has: I can monitor my blood sugar while taking a yoga class. I can know that I’m 77, but stable, so no need to correct. I can know I’m 122, and heading up, so better get moving. Sigh. I love medical advancement. I love healthcare.

And an additional note to those of you without continuous glucose monitoring, which is likely most of you: fight for it, it’s worth it. If you’re with Kaiser, send me an email, and I’ll tell you what the magic words are. And if you have any sort of sway with the government, or with healthcare providers, make it loud for sake of the rest of us diabetics: please help us get the tools we need, not to live normal lives per se, but to live healthy lives.

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Michelle L
Michelle L
13 years ago

Thanks for great article!  I was  amused by your frustrations with the wait and the needle- in an empathetic way of course!  Two of my children wear the Navigator cgm.  It has a TEN HOUR wait after insertion!  I HATE it! Our  sensor is encased inside the insertion device so we have no choice as to how we get it in, nor can we see the needle that does the job.  Good for my kids, but after a few insertions, I was curious.  I had to get a large hammer to smash one open so I could see the needle…glad… Read more »

Dr. Margaret A. Morris
13 years ago

To everyone interested in the ins and outs of the Minimed CGM, I found these two sites very informative:

An intro to the mysterious ISIG value, and a lot of discussion about sensor habits:
Even better, a one-man experiment and explanation of how the BG reading is calculated from the ISIG:


Jeff Nobles
Jeff N.
13 years ago

I’ve uploaded a PDF of my first few days’ data in the Medtronic format, here,, for anyone who wants to see it. It’s 10 pages of data for less than three days, and much of it is unintelligible to me so far. Medtronic’s data usage policy says they are using the data and sharing it with third parties, but not for marketing purposes. Wonder what they’re using it for? Hope it’s being used to advance the technology in light of user experience. Like Bernard, I’d like to have an app that’d let me extract and use the data to… Read more »

Dr. Margaret A. Morris
13 years ago

Bernard– I haven’t seen it yet, but I expect it’s only in a proprietary data format. And I’m not saying anything, so as not to violate any warranties, but if the data’s there, I’ll find a way to get it out in a format I can use :) I’ll keep everyone updated as that project progresses, of course.

Bernard Farrell
13 years ago

Glad to hear it’s working, it was fun to hear your almost drool about the data. It’s a pet peeve of mine that we can’t easily interpret the CGM and insulin data.
Maybe Minimed’s solved that, but I’d also love to see 3rd party solutions that can extract and use the data…but it’s probably stored in ‘proprietary’ form.

Dr. Margaret A. Morris
13 years ago

Paul– I’m glad to hear that– I look forward to seeing all the output! Jeff– Well, FireFox in a virtual machine is still better than IE in a virtual machine, I guess. But it just reinforces my feeling that diabetes software is many steps behind where it needs to be. I’m glad the sensor is working well so far for you; I have been extremely happy thus far– my blood glucose levels are so much easier to monitor and attend to! I am slightly concerned that I will over-react as a result of too much data, but so far, things… Read more »

Jeff Nobles
Jeff N.
13 years ago

Karmel, Minimed used to give that USB key away, but I’ve read they charge $60 for it now, and the price will soon rise to $99. I use the software with Firefox; the program will tell you it works only with IE but it’s possible to click through that warning and use Firefox anyway. But it doesn’t work with the Mac OS, so you’ll have to use a Windows PC or have Windows loaded on a Mac. This first sensor has worked well for me (I’ve worn it since Saturday morning). I woke up yesterday morning with a surprisingly high… Read more »

Paul Sorensen
Paul Sorensen
13 years ago

I used the Minimed CGM for about a year.  I was impressed by the Carelink/Minimed site.  Since the CGM checks BS every 5 minutes, you have a ton of data to analyze.  The graphs were very useful for trending, dayparts, targets, etc..  My Endo and I were able to zero in on specific areas.  If you like crunching numbers,  you’ll  love it.  Good luck!

Dr. Margaret A. Morris
13 years ago

The Minimed system does have trend arrows– I haven’t seen exact mg/dL translations anywhere yet, but basically one arrow means movement up or down, and two means faster movement. The Minimed does not have predictive alarms, which seems like a nice feature. But I love having the readings incorporated into the pump– the fewer extra pieces I have to lug around, the better. I had tried the Dexcom CGM a while ago, and thus far the Minimed seems slightly more accurate and consistent, and much more convenient by virtue of the pump integration. The part I haven’t seen yet is… Read more »

Jennifer Jacobs
13 years ago

Congratulations! That is a huge achievement (getting insurance coverage for your CGM). I’m very interested to hear your thoughts on the minimed system. I’m on a Paradigm pump, like you, but I have the Abbott Navigator (10 hours’ calibration — really?) because it had predictive alarms and a bigger screen. But it looks like, from your picture, the minimed system has trend arrows, too. Do you know if it has options besides just up and down? (The Abbott has a diagonal up/down line, meaning you’re rising/falling 1 mg/dl per minute and then a straight up and down to indicate a… Read more »

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