Dexcom Questions part 2 (and How to Save Money with Your Dexcom Glucose Monitor)

Here are the questions I’ll answer in this post:

How are you going to teach me to save money with my Dexcom Glucose Monitor?

How do you get the sensor to stay stuck?

Sounds messy.  Is it?

I did all that.  My sensor still failed early.  Now what?

I saw some Dexcoms on blogs that had cool silicone skins on them.  Where do I get one?

What do I do when I get those ???s ?

What’s your biggest complaint about the Dexcom?

How are you going to teach me to save money with my Dexcom?

In order for my technique to work for you, you have to be  1.  a little bit lucky and 2. not 100% devoted to FDA guidelines.  Dexcom would DEFINITELY not endorse what I’m going to say here.  Clearly some people out there are doing this, but some are definitely not.

The sensor that I’m currently wearing has been in for 16 days.  The one before that for 15.  In fact, the last 3 sensors I’ve used have all AT LEAST doubled their approved length of use.  But it took a while before I was able to achieve this.  In my early days with my Dexcom, I would have sensors fail after 4 days, 2 days, sometimes less than 24 hours.  Now, Dexcom has EXCELLENT customer service, and would always quickly send me new sensors to replace any that did not last the approved 7 days (make sure you save your packaging until after your sensors have survived 7 days so you can give Customer Service the Lot# and SN of the sensor- it helps them know if there was a bad batch) but it’s a pain to have to re-insert and recalibrate twice in one day.  Once, my sensor failed after 2 days, on Thanksgiving (where I needed it the most!).  I think it may have just been too afraid.

From my experience, the two factors that have the greatest impact on sensor life (aside from manufacturing inconsistencies) are quality of adhesion (more on this) and site selection.  For me, I only get long life when I apply the sensor to an area with some fat to it.  At 6’6″, 195 and active, that gives me very few options.  In fact, in terms of sites I can access by self, it gives me two options, about 1″ below and 3-4″ to the left or right of my belly button (give or take 1-2″ in any direction, depending on where your waistband hits etc.).  My endo, who did a video on CGM for TCOYD, likes to wear his on his thighs.  Maybe I don’t have enough flesh there, but I haven’t been able to get a very long life on my thigh.  Your miles my vary.

Anyway, play around.  My out-of-pocket for sensors is still significant, and every 7 days of extra sensor life is like getting one for free.  That can really add up.  That said, there’s no point in pushing the life of a sensor that’s not doing what I need it for.  A CGM is useless if it’s not giving you good numbers, so no matter what, if a sensor gives me numbers that are consistently over 10% off of what my finger stick gives me, I change it.

***In order to get your receiver to recognize your old sensor, when it says “Change Sensor Now” just press “OK” and go to “Start New Sensor” as you would if you had put in a new sensor.  It will initiate the same 3-hr calibration, and then ask for 2 start-up BGs, just like a new sensor.  You don’t have to do anything different.

How do you get the sensor to stay stuck?

This is a particular challenge for me, especially when I’m spending a lot of time in the water.  Obviously, Dexcom has to strike a balance between an adhesive that stays on well, but not so well that you can never get it off.

Here’s what I do.  Since I only really use two basic sites, I have a very consistent routine. I try to make slight variations in actual location to be safe, but since you’re not pumping anything through the sensor, the sites don’t get irritated/scar like pump infusion sites.  Also, 14 days tends to be more than enough time for the previous site to heal.  First, I shave the area with a regular disposable razor, to get the smoothest surface possible.  Then, I prep the area with Skin-Tac alcohol wipes (it is also available as a liquid though I haven’t used it, and try to avoid liquids due to the hassle of flying with them.  The wipes can be stored anywhere).  I rip the packet in half so I don’t have to touch the sticky part, and apply it liberally to the area I’m going to stick my sensor.  Then I LET IT DRY COMPLETELY.  Then I carefully apply the sensor adhesive, making sure that it’s entirely flat.  It’s very important to do this while you’re standing up.  This is when your skin is most taut.  If you do it sitting/lying down, you will feel the adhesive pull off a little when you stand up.  Press everything down, push in the needle, pop in the transmitter and you’re good to go (if you don’t have a Dexcom or have never inserted a sensor, this process is all illustrated on their website).

If this isn’t enough (and sometimes, after a lot of time in the water/at the gym, the adhesive starts coming loose) I just tape it down on all sides. Some people do that proactively, which makes sense too.  You can use any medical tape you like.  Paper tape will be gentler, but also less robust.  I just ordered a roll of Opsite Flexifix to try out {update 4/24/10- I LOVE the Flexifix.  It’s a little delicate to work with (very thin and sticky) but once it’s on, it’s like skin, and will clearly last longer than any sensor.  I’m a convert}.  Some people use Tegaderm patches, cut to size.  If you do use something like this, I recommend cutting out a window for the transmitter to stick through, so as not to interfere with the signal at all.

Sounds messy.  Is it?

Sometimes, all this adhesive can leave a lot of residue on the site.  While I don’t worry about it too much (people are more likely to notice the big white thing a couple inches away), if you rub gently with rubbing alcohol, sooner or later it comes off….usually later.  Don’t be too aggressive, it’s easy to give yourself a rash. If you want something more aggressive, Skin Tac also makes adhesive remover called Tac Away, but I personally haven’t tried it.

I did all that.  My sensor still failed early.  Now what?

First, call Dexcom Customer Service at the number on the back of your receiver (877-339-2664).  Give them the Lot and SN of the sensor, and they will send you a replacement (always make sure you have extra sensors in case one doesn’t go the distance).  Another thing you can do is upload your receiver data to Dexcom for them to evaluate and see if there was a problem with your transmitter/receiver or if it was just a bum sensor.  Customer service will send you instructions on how to do this if you ask (it takes less than 5 minutes using the software that came with your Dexcom).  You then have to call them once your data is uploaded, as they do not get notified automatically.

I saw some Dexcoms on blogs that had cool silicone skins on them.  Where do I get one?

I had this question FOREVER.  I forget where I saw the first one, but I went on a Google odyssey looking for them and came up dry.  None of the pump case/meter case people had them.  But I contacted Dexcom customer service, and lo and hold, they have them for sale through Dexcom (no idea why they’re not listed on the website, but they’re not).  Call Dexcom, extension 3, and they are $10, plus shipping, in the colors seen below.  For a pocket-user like me, these are perfect.

I chose blue for visibility

What do I do when I get those ???s ?

Great Question.

Here’s what Dexcom told me: “That ??? icon indicates something occurring internally with the sensor wire.  The good news is it doesn’t indicate anything with the hardware, or that the transmitter and receiver aren’t communicating. “  Which is  sort of good news, but it doesn’t necessarily tell you what to do.  I will say that, as my site selection technique has improved, my incidence of ??? has diminished, and it really only happens anymore towards the end of a sensor’s life.  I usually wiggle it around for a few minutes and then wait.  If it doesn’t come back within a few hours, I change sensors.

What’s your biggest complaint about the Dexcom?
I really don’t have any big complaints, but it’s also the only CGM that I’ve had.  My three main criteria are comfort, accuracy, and ease of use.  I rate the Dexcom high in all three categories.  If I could change something, I would definitely make the alarms more flexible.  As it is, your high alarm is limited to 20mg/dl increments (100,120,140,160 etc).  Personally, one of the things I wanted to do when I got used to wearing my Dexcom was slowly step down my upper limit.  I started on 180.  Going from 180 to 160 is a big jump, and I tended to get a lot of high alarms in the beginning, even if I was peaking around 160.  It would have been nice to go 180, 170, 160 etc.

The other thing I wish I could do is travel in time more.  What I mean by this is that while you can view your last 1,3,6,12 and 24 hour graph, you can’t see a 3-hour graph from any time period except the present (except using the software on your computer).  You also can’t go back and enter a carb event or an insulin event after the fact if you forget (the result of this is that I don’t enter those events anymore.  I was forgetting too often, making the data incomplete and of little value).

I hope these tips are helpful.  If you have any other questions, leave them in the comments and I’ll try to answer (even if it’s long after I posted this).  Or call Dexcom customer service.  I’ve never had a bad experience with them.

Next, I’ll post my worst Dexcom experience (which wasn’t at all their fault).