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One of my criteria for my timing of moving back to Canada was approval of the Dexcom G4 in Canada.  I rely on the Dexcom so much it’s almost disturbing.  For me, it’s been crucial in management of blood sugar and hypo prevention during exercise.  However, I have yet to localize my CGMS receiver, so it still reads in mg/dL.  Since that’s an out of pocket expense, I wanted to see if it made sense to get a mmol/L receiver, or if the newly approved Animas Vibe would be sufficient.  For those not in the know, the Animas Vibe integrates the Dexcom G4 CGMS with the unit.  It’s basically an upgraded Ping (although some would argue losing the remote meter is a huge deal), with lots of UI and usability adjustments and CGMS on the unit.  Rather than review the Animas Vibe as a whole, what I wanted to do was review the Animas Vibe vs. the Dexcom G4 standalone receiver – which one is better for exercise?  Is there still a place for a Dexcom G4 receiver, or is it redundant?  Is there a place for both?  If I had to choose, which one would I go with? The Newfoundland Animas rep sent me a surprise e-mail on Wednesday offering me a loaner Animas Vibe.  She knew I was keen on trying it out.  The extra surprise – it’s an awesome pink unit.  So I made plans to do a long run this weekend to see how the Vibe would fare – running is the one activity where I sometimes find I run out of places to put things; and the fact that the Dexcom receiver is not waterproof makes it a necessity to carry it in a LokSak or ziploc bag depending on the weather. So without further ado, I powered it up, programmed it, and calibrated the CGMS the same as my receiver.  Since my receiver was already running the numbers were slightly different.  So Friday I took it on a bike ride, and thanks to the combo of old sensor and noise/friction from the wind jacket I lost the reception.  At least both units failed.  What’s interesting is the Vibe actually gave an error (and stopped the session), whereas the Dexcom receiver just showed a “lost signal”.  So I put a new sensor in and got them both running with the same calibration – good news, they showed the same results.  I’ve had this issue with Dexcom sensors before – it’s a combination of materials and sensor age that seem to lead to the lost communication.  You can just restart, wait two hours and grab a new calibration, but my sensor was plenty old. I also made plans to try and run my first marathon – why not go big or stay home! 🙂  I’ll write more about that in another post, but let’s try and trim this one down and write about what I liked and didn’t like and what I learned.  As usual, I started the run with my usual pre-run oatmeal.  You can see my multinational setup – mmol/L and mg/dL playing together!  Trust me, they are the same readings.

Pre race, real food, and diabetes tech

Pre race, real food, and diabetes tech

So, jokes aside, what did I think? Here’s a few talking points:

  • First of all, the best part – this screen.  It shows the time, your current CGMS blood glucose, the trend arrow, and the insulin on board.  This is almost everything you need to know, and the real value of having the units integrated.  It’s a great screen, and the one I leave hotkeyed on the pump.  Why do I say almost?  Well, sometimes my sugar can start creeping up ever so slowly – the Dexcom algorithms still say it’s flat, but really it’s a slow creep up until I hit a high.  So that flat can be misleading which is why it’s good to also actually see a few data points.  You only get that on the pure graph screens.  Still, if I am running, this is the main screen to see.
Best screen ever - CGMS, trend arrow and IOB

Best screen ever – CGMS, trend arrow and IOB

  • When you zoom out, the CGM graph is actually kinda hard to read on the Vibe, and this is my major pet peeve.  The Dexcom screen is just bigger, and on top of that, they colour the dots white.  Also, note the Dexcom shows time stamps so you have an idea at what time your trends are firing off.  The markings are there on the vibe, but really not as easy to read.  If you wanted to be scientific with your trends, you’d have to look at the time (4:53 pm in this photo), then figure out the scale (3 hours, so 6 ticks, so each tick is 30 minutes), then back off from that.  At least on the Dexcom I can quick glance and see that around 1:30 PM I had a low alarm.  I also find the green just harder to read.  Dexcom’s colour scheme is red(low), white (in range) and yellow (high).  Maybe it’s just the change to green that messes me up, but I found it a bit harder to read.  Maybe it was my tinted sun glasses.  Finally, font size is much smaller, especially on this screen – the blood glucose value is just harder to read than Dexcoms (and also harder to read than the above screen that I love).  It’s all just a function of smaller screen real estate.
3 hour graph, less readable when you have tight control

3 hour graph, less readable when you have tight control

  • These problems become more exacerbated when you zoom out.  Now, for exercise purposes, you aren’t really going to be looking 6 hours (unless you’re doing an ultra) but for every day use this screen starts to lose it’s utility.  If you were trying to make decisions on your blood sugar management based off this it would be tricky – you’d be better served to upload it to try and read it.  I’ll touch on this later.

    6 hour trend

    6 hour trend

  • The final photo evidence useability feature I want to touch on is thickness.  The Dexcom G4 is svelte; it’s like an iPod.  I find it very easy to slide it in and out of my tights pockets.  All my running clothes are spandex – short tights and long.  The hip pockets on these tend to be quite snug/compressed against the leg.  The Dexcom easily slides in and out for a quick glance.  I found myself having to fight to pull the pump out.  This is also true of the Ping; however, I consult my Dexcom a fair amount and only pull the ping out to bolus.  So this meant I spend more time trying to slide this in and out of my pocket.   If you have numb fingers (like I did for the first half of this run) it can make it quite challenging!


So what else did I learn from a usability stand point.  Here’s a short list of pros and cons. For the Vibe:

  • Waterproof – you could use this during a tri and not worry about leaving the receiver in transition.  Also, you would not need to bag a receiver like I do on a wet day.
  • Integration means that if you need to action a BG you already have the pump out.  So there’s an efficiency there.
  • Glucose trend and IOB on one screen – pure gold
  • You can’t drop it – since you’re hooked up with tubing you really can’t drop it on the ground and loose it.  Well, at least you’d have to try really ahrd.

For the Dexcom:

  • Having a separate unit is perfect for sports like cycling where you can mount it.  It’s much more convenient on the bike than trying to read your glucose off the pump on a bike.  My pump sits in my jersey and rarely comes out.
  • Access to data – this is almost the key part to me.  To get your CGMS readings off the pump you need to use Diasend.  Diasend is an amazing website for integrating glucometers, cgms and pumps; however, it does not export data in raw formats like Dexcom Studio will.  Now, I do realize that the Tidepool project has ways of doing it, but this is not for the every day diabetic.  I love data, and the Dexcom’s USB port makes it possible to upload to Diasend AND Dexcom Studio.  Dexcom studio will dump any data available into a tab de-limited format.  I also like how Dexcom Studio does trends and identifies areas you are going high/low.
  • Readability – the separate receiver is just better to read
  • Range – I noticed the G4 receiver has a much longer range to communicate with the transmitter.  You may not think it a huge deal, but I can envision scenarios where one may disconnect and leave technology behind – like crack climbing.  I’ve been up an 80′ pitch and left my Dexcom on the ground and still had reception.  The Vibe just won’t – probably battery life related.
  • Form factor – if you frequently check your glucose, getting the Dexcom out to look can be much quicker and easier to do since it’s so small.
  • Speed – the screen refreshes on the Vibe are slow whereas the Dexcom renders much faster
  • Alarms – sometimes I don’t feel the vibration alarms; however, the Dexcom alarms are also extremely loud.

Overall, if I could only have one, I’d choose the Dexcom receiver.  It’s versatility to work well with every sport makes it a clear winner.  On top of that, readability is key.  Now I’m not saying the vibe isn’t an amazing product – it really is and I do hope to get one.  It makes running simpler to plan, and for a long run it makes blood glucose management even easier with that one magic screen.  However, that one screen, while amazing, is still no match for the total pack of the standalone receiver.  Besides, in every day life I like being able to set my CGMS on my desk and work away.  I don’t have to take my pump out to look at my levels.  That goes a long way to feeling like we have a “normal” life.  I plan to localize my CGMS receiver soon; and hopefully check a Vibe out in the near future.  Both are great, but the Dexcom is my first choice for CGMS usage.  I don’t think they are redundant – but I do feel like one is a better all-arounder. Summary:

  • Vibe is a great product, it really fixes a lot of usability issues with the Ping (but you loose remote bolus)
  • Dexcom receiver is a better all around CGMS receiver
  • For running and swimming, Vibe may be a better solution
  • For cycling and rock climbing, I’d rather the Dexcom
  • For every day use, the Dexcom is more useful to me