Sensor placement

This is the thing I was wondering with leaving the sensor in place for an extended period of time (more than 7 days).. if that causes the hardness of your skin, tissues, scar tissue or extra fatty deposits or whatever like if a person may use one site a bit too often like when giving insulin injections. Can I ask you your experience with that? Just saying, it would be better to not have to use the same possible rotation sites as for the insulin. My son was dx'ed 12/11 & is so good w/ his attitude & care. Even still w/ rotating, he has to avoid his left arm (favorite spot) for sc injections for awhile b/c it's a bit overused. He thought it was getting a bit more muscular, not damaged so that freaked him out some. He obviously doesnt want to feel like he'll run out of spots to use. So have you noticed any ill effect to your skin, tissue, muscle quality from using the sensor itself?

Lipodystrophy is caused by the insulin itself, not by the physical damage of the needle stick. Basically, the high concentration of insulin around the fat cells where it's injected cause them the metabolically react -- just as they do with plasma insulin -- and absorb and process glucose into fatty acids that are then stored.

So, if you inject at the same site again and again over an extended period, those local fat tissue will react as if it's bathed in high-dose insulin all the time; the cells will get "engorged" on sugar, literally get fat, and this all manifests at the macro level as a small, harder bump of tissue.

The G4 is passive -- doesn't introduce anything into the environment where the wire is that is metabolically active. So, there is no risk at all of developing anything like lipodystrophy.

looking at the top of the thigh and measuring from knee to groin, about where do you place it, in terms of percent from knee? (knee = 0%, groin = 100%)

I'm getting ready to put #2 on tomorrow, and I'd like to try the thigh.

It’s about 75-80%…pretty high up on my leg. Good luck with the new site!

I took a photograph today of my thigh after 28 days of sensor wear. You could not tell that I had actually had anything there for 28 days, never mind a sensor and some opsite flexifix tape. There is literally no mark at all. The omnipod canula causes far more damage in 3 days than the dexcom in 28 for sure.

Mine is equally high, at least 80-85%

I've been using my abdomen, but would like to try the thigh to give my tummy a break. Do you place the sensor vertically (knee to waist) or horizontally (around the thigh)? On the abdomen, I've placed it horizontally, but I can't imagine it in that position on my leg.

Vertically, although I know some folks do wear theirs horizontally…that seems strange to me on my leg, but of course, ymmv!

I tried my thigh once years ago, and it pulled off within 2 days while I was putting on my jeans. You thigh people haven't found that to be a problem? I'd love to try somewhere new, since I've been doing it exclusively on my belly (for over 4 years!) since then.

Also, when using adhesive tape do you guys put it on immediately when you first insert, or wait till the sensor's native adhesive starts to pull a bit at the edges?

Well, tried a new spot today -- 3" above my left knee, top of thigh.

We'll see how it goes, but so far, I like it a lot. Major pluses:

  • Super good control over the insertion. Sitting on my bed after showering with my legs straight out, applying the sensor and then controlling the insertion so it angled just right to slip under the skin but not go too deep was a breeze.
  • Quite comfortable spot.
  • No interference with clothing, pockets, etc.
  • Do not constantly "feel it's there".
  • When the time comes to deal with failing adhesive, the access will make it really easy to get it tacked down good again with some SkinTac.
I struggled with many of these issues when I was placing it partway around on my back (love handle / kidney area).

If the accuracy is good as usual, and the sensor lasts past at least 10 days, this may become my new favorite spot. I try to keep the upper arms free for the Omnipod.

Well, so far a disappointment. All the pluses are still true, and it's a fantastically comfortable location. However, the accuracy has been horrible. Also, this afternoon I got that situation where you have a reading, seemingly flat trend, but no trend arrow.

Not sure what that means, but I think it means the G4 can't figure out what the trend is, which is troubling when it's flat and I'm in fasting mode (4 hours after lunch).

I'll stick with it for a few days before I throw in the towel and waste a sensor. I sure hope it's just a rough start on this wire, and it settles down to the usual impossible accuracy it seems to have for me :-)

Dave,
I was always wondering why Dexcom cannot see the trend when I clearly can. My theory is that the trend shown on the receiver originates from the transmitter and is based on a 5 minute window. In the 5 minute window the measurements might not show a trend but once the measurements are condensed into one reading the readout on the receiver clearly shows a trend. In my opinion this is just poor engineering. If an observer of the receiver screen can spot the trend then the receiver should show the trend. I wish Dexcom had better engineers on their payroll.

In light of the amazing accuracy of the G4 sensors (compare the alternatives), it strikes me that Dexcom must have some pretty good engineers on their payroll!!!

I suspect that the transmitter is pretty dumb and doesn't do any of the algorithm work. Unlike medtronic's minilink, the Dexmitter doesn't even retain and re-transmit readings when the receiver is out of range.

The trend arrows seem pretty pointless anyway. A visual examination of the 1 hour trendline gives an excellent indication of where the numbers are going, much more accurate than the arrow. I can often see that it is moving up or down when I have a flat arrow. Also, after using it for nearly 6 months I have still not seen a double down arrow. Does anyone ever get these or is it just me?

I have been using the Dex since November 2012. In that time I have seen maybe 3 instances of double down arrows, and about the same number of double up arrows. They are invariably the result of severely miscalculating carb counts or effect of exercise.

I wear the dexcom now but have been using more fatty areas of my belly, etc. I want to try arms and legs but have very little fat in them. Will this be a problem? I'm terrified of hitting muscles when inserting..I hear that doesn't feel too good. Anyone know how long the insertion needle is?

Thursday... to follow up, the sensor was pretty wonky the first day, but has settled down and is behaving as usual. I'm happy.

One tip, though: Do not put it on top of the thigh you preferentially cross your other leg over!! When sitting in a chair with my leg crossed (right leg ankle on left knee), I hit the thing again and again. I never cross the other way, so from now on, right thigh top only!

Also, the location is getting a lot more bumping and stuff, so the trendline has those little wiggles in it that that doctor said are a sign the sensor's about to fail. It's working great, so I guess that symptom of sensor burnout isn't useful for me when it's on my thigh.

My favorite place for stuff like this is my upper arms. Problem is, I put my Omnipod there, that gets changed every two days, and I like to alternate arms.

I've avoided have both the sensor and the pump close to each other worried about the sensor data being affected, but there's been quite a bit of good data from various research programs (the artificial pancreas studies in particular) that indicate this isn't a concern. I think I'll try my next one on an arm, with the pod there too.

As for the inserter, not sure what the depth is, but it's small -- something like 4-6mm. The biggest issue is it's just quite a chore to insert the wire with one hand.

Tried the back of the arm. Painful!!!! I don't have any fat.

Abdomen only. Nowhere in the manual does it say it's okay to use anywhere else.

Yeah Khurt I read the manual, but nowhere in the manual does it say to restart the sensor after a week to get more time out of it. My last sensor was accurate for 26 days on the back of my arm. The manual may be useful for some things but for things like sensor placement I would rather rely on the opinions of people who actually use the device than someone constrained by the FDA.