Day 2 with the Dexcom

So it's been a good day and a bad day.

Being a technology geek, I took to the Dexcom fairly quickly. I didn't feel the need to press the button every 10 minutes to see what was happening to my blood glucose levels. But I was able to use it last night to see where the levels were going.

And I was woken up around 3 AM because my blood glucose had crossed the 200 mg/dL High level that I'd set. I was able to see how the numbers had been cruising up that way for over an hour. After I corrected and went back to bed, I woke up with a glorious 145 mg/dL at 6 AM.

Later in the day I was able to watch my levels rise up to over 300 mg/dL sometime after a larger than usual breakfast. And also catch then plummet below 80 mg/dL after a strenuous afternoon cleaning out the goat shed. Whew.

Here's a picture from a short time ago. Click on it to see it larger. It shows the frustration that can happen when the receiver moves out of range of the transmitter. See the three dashes on the upper right? It's not getting a reading at the present. After I started writing this post it picked up the signal again and all is good.

Newbie Impressions of the Dexcom

Here are my first impressions of the Dexcom. These are some of the reasons why I see this as a V1 product. I'm sure the Dexcom folks will have a newer version before too long, and I hope they'll fix these issues. Please bear in mind that I think a lot about user experience, so I tend to think about aspects of the device that may not bother others.

First of all, for the device to work it needs to be synchronized from time to time with a OneTouch Ultra meter. Now I already use a OneTouch UltraSmart meter, but I can't use that to synchronize. The only meter that's supported is the Ultra. There is no means to hand-enter values for this purpose.

This is a fairly big barrier to entry. It increases the Total Perceived Pain of Adoption that Pip Coburn mentions in his book, The Change Function.

Another minor nit here is that a cable is provided solely to connect the Dexcom receiver and the Ultra meter. This is something that you will need to do several times each day. The cable is over 6 feet long. But the receiver can't be more than 5 feet from you, and your meter is probably going to be right beside you. Why doesn't Dexcom provide a smaller more portable cable? How about something less than 12 inches in length.

The receiver itself is very large. It's a sealed unit that must be recharged with a provided transformer. According to the manual a full charge takes about 3 hours and will last about 5 days.

I compared the size and weight of the receiver against my Minimed 512 insulin pump and the details are below.

Unit	Dexcom Receiver	Minimed 512
Weight	2.875oz. 85 grams	3.75oz. 110 grams
Height	2.25 inches. 5.71 cm	2 inches. 5.1 cm
Length	4.25 inches. 10.8 cm	3.25 inches. 8.3 cm

In summary, the Dexcom won't win any awards for compactness. It's a little lighter than my pump, but it's bulkier all round. And forget the carrying case that's provider. That substantially increases the bulkiness. Besides which, where are you going to strap this? With a cell phone on one hip and, for many likely Dexcom users, an insulin pump on the other, there's really nowhere else to hang a large bulky black object.

Having a shower is a real pain. I used one of the shower protectors that I received. And I had one of my usual short showers (less than 3 minutes from start to finish). But I still managed to get water between the transmitter and the sensor. Which caused the readings to go crazy. So that I got the big black X in the receiver screen meaning that it had gone out of calibration.

I dried the transmitter off. Tried waiting for about 20 minutes with no luck, and had to reset the receiver as if I had inserted a new sensor. That meant a 2 hour and 15 minute wait until I was receiving readings again. You can see all this in the picture above. The ever-higher readings, followed by a big gap, followed by readings again.

When it's working the entire system has been very enjoyable so far.

I've requested a copy of the software from the Dexcom rep, because I don't think I can really judge the system without seeing what the software provides. Currently I'm frustrated that it's hard to use the screens combined with the receiver to see what was happening (for example) at lunch time today.

To my mind, the inability to go back in time longer than the previous 9 hours is a big weakness. I'd love to see what happened the day before, or maybe a week ago. I'm hoping that the software will make up for this in some way.

I'll try and post more on the Dexcom in a few days. If you've any questions, please ask.

Labels: CGM, Dexcom, gadgets

posted by Bernard @ 9:35 PM