Have only tried 2 sensors. The first was too far to the side and I was putting pressure on it and driving false lows. The other I put too close to my rib cage and too close the midline of my belly and this caused 40 point variances as well as false lows at night (may have hit muscle). Hopefully I find a spot that is close enough to my belly button that a sensor isn’t smothered when I lay on my side.
In the Seven Plus Quick Start Guide, it says if you wear an insulin pump, make sure the Sensor is placed at least 3 inches away from your pump infusion set.
i used the decom but then gave up on it cuz it would be way up. and it seemed that if i put all my readings in it it would make a huge diffrence and be like 100 points then of my actual blood sugar
I enter in my bg every single time I test with my meter and it does seem to make it more accurate for me.
Have you ever had an infection from leaving it in that long?? I’m worried about leaving it in for more than 10 days at a time just due to sanitary reasons.
The FDA is not Obama’s. Most are career civil servants or outside consultants. The rules are made by Congress and the last major changes in the approval process came under Bush. I hope crow tastes good!
Everyone has their story. Here is mine. I have been wearing a Dexcom 7+ for almost two years. My self taught rules are:
- Do a finger stick and tell Dex with every bolus.
- If Dex wants a finger stick, do it and enter it.
- The more finger sticks the better. Get a person with a degree in statistics to explain the math.
- Do not do two or more finger sticks in 10 minutes or less except for the initial start-up double stick.
- Always test fingers prepared by the book. Non-finger sites (arms, etc) risk dilution with sweat when you are hot, hypo, or sick and therefore are NOT ACCURATE.
Results:
- My readings are close to BGs most of the time. For me, close is ±10% for each and the values should overlap. For example 120 and 100 are good (120 - 10% = 108 and 100 + 10% = 110, therefore, this example overlaps by 2).
- Keep in mind, a BG is blood and the CGM is testing interstitial fluid - get a good grip on this and you will understand the reason for the time delays and other reasons the values may not be dead on every time. It is the TREND to work with for control.
- When in doubt, contact tech support or the local Dexcom Clinical Manager. Learn from the people trained to know.
Hope this helps.
Jay
Did Obama not nominate the current commissioner of the FDA Dr. Margaret Hamburg? It is my understanding she is the one who put the brakes on device approval as well as other things. A quick google search of Obama and FDA yielded:
In a Tuesday Wall Street Journal op-ed piece, President Obama announced a newly signed executive order that pushes for more efficient regulation throughout government agencies, including the FDA. “The FDA will lay out a new effort to improve the process for approving medical devices, to keep patients safer while getting innovative and life-saving products to market faster,” Obama explained. But the new guidelines had some in the community worried as they wait to hear how the changes would be implemented.
How are the rules made by Congress if Obama can sign an Executive Order that “pushes” for anything the FDA is doing? Seems as if the politics of the FDA aren’t as simple as Congress makes the rules.
Hello Mike,
I have been having a hard time with my insurance paying for the dexcom machine and sensors. I will be receiving my kit in about a week. Can you tell me how to extend the life of the sensors? What is the procedure and how do the results vary as the days go beyond 7 ? How are the results on the 14th day (as an example) as compared to the accuracy of the fist week? Would you recommend going into the 4th week or just go an extra week or two past the recommended 7 days? $300 a month is beyond my normal means, this extention would give me the ability to use my dex machine on a full time basis. Thanks…
For me the most common reason a sensor ever fails is the tape coming loose and the sensor wire getting pulled out completely or partially. Therefore my primary way to extend the life is to add extra tape (I use Flexifix) once the edges start peeling off. The Dexcom tape usually makes it to the two week mark before I need to add something to hold down the top edge. I realize that results will vary for different people but I just keep restarting the sensor as long as possible but replace it as soon as the results become wacky. The 28 day sensor that I posted above actually failed on day 29 and that’s the longest I’ve ever gone. Three weeks is most typical for me.
I’ve never noticed any infection. For me the sensor site always looks the same whether it’s removed at one week or three weeks. It always looks like a small red pimple that clears up after a few days. I’ve seen people complain about itching but fortunately I’ve never had that. I’d be more inclined to remove a sensor if it was uncomfortable but I now usually forget which side it’s on until I feel for it.
Wow Mike, my dexcom tape starts to peel at the edges in a few days, on goes the flexfix which seems to last forever!
Just started my 3rd week on this sensor yesteday AM - longest I’ve been able to go so far. I really like this sort-of-inner thigh site.
Folks, I just found TuDiabetes yesterday, but I’ve been a DexCom (Seven Plus) user for over two years, and T1DM for over thirty years (see my page).
Disclaimer: I am NOT a physician, nor a nurse-practitioner, nor a diabetic educator. I’m actually a self-employed IT guy with a background in helping build rocket ships. (I was a dual-major in college–Aerospace Engineering and Automatic Control Systems Engineering). I CANNOT and WILL NOT guarantee the accuracy of anything I relate here for any purpose other than helping others find their own paths toward less uncertainty in managing their diabetes.
That said, I can corroborate much of what others have described here. Basically, it’s a mistake to view the precise number on the DexCom or on a finger-stick meter as absolute gospel. (At one time I had a graph from a clinical study on the DexCom that showed its accuracy performance over the range of BG levels it can detect and report, and that indicated–I believe–that its performance was superior to other CGMs on the market, especially in the low ranges–if I find it again, I’ll post it here–DexCom does have some information about clinical results on their web site: [click here]) So we all have to rely on a combination of inputs to make decisions about carbs and insulin. Having the DexCom is not a panacea, but it sure is a vast improvement over its lack (corroborating Mike’s comment).
For me, the single thing the DexCom has added that is valuable beyond measure is the ability to report BG rates–how fast is my BG level rising or falling. If you grok elementary differential calculus (…and if you don’t, don’t worry, just ignore what I’m about to say…), what we’re talking about is the time-rate-of-change of the blood glucose level – dBG/dt – also known as the slope, or the shape of the curve. Even if the immediate BG value on the DexCom is off from what a clinical blood test would indicate in the same instant, the recent shape of that curve is still pretty much the same. And I, frankly, am way more anxious to know the trend than simply whether or not I’m at a low (or a high) value this moment. Not to diminish knowledge of current BG values in any way, it’s just that if you know you’re heading downward, but not there yet, you can do something about it (I know I’m preaching to the choir here). No tool before the DexCom has ever had this capability (though I imagine other CGMs have similar functions).
Sensor site. I have several small benign lipomas (fat tumors) on my abdomen. Once in a while I manage to get a DexCom sensor stuck into one. The lipoma tissue is not vascualized like ordinary dermal tissue, so the interstitial levels of everything, including glucose, are not what the DexCom is designed to work with. When I do hit a lipoma, I usually wind up having to toss the sensor and start a new one a few hours after it warms up (corroborating Richard157’s comment).
Calibration frequency. When I first got the DexCom, I was so in the habit of doing a finger-stick at every meal, that I was calibrating it every time I did one. Then my endocrinologist reminded me that the DexCom specs only require two calibrations per day. Duh! Personally, I have not noticed any difference in the DexCom’s accuracy (to the extent, of course, that I have data to judge by) between 2-a-day and 5-or-6-a-day calibrations (re jrtpup’s comment). The comments about not calibrating when BG rates (up or down) are high is also something I can corroborate.
Reusing sensors. I’ve experimented with doubling the sensor’s nominal duration (going two weeks). Mostly, it seemed to work fine, although in the second week the adhesive tends to come un-stuck around the edges. But I’ve also had a problem with not hearing the low alarm when I’m asleep, and that plus the variations in accuracy that do occur made me decide to go back to 1-week durations per sensor. Your mileage may vary.
So technically, are there inaccuracies in the DexCom (and for that matter, in your BG meter)? You bet. Is having the gizmos better than not having them? (<–Note: rhetorical question).
Welcome to the family James!
I’ve gotten up to 19 days from a sensor; the most I’ve heard of is 31 days. I find the second week even more accurate than the first. The lifting adhesive issue is easily solved. I use a product called Opsite flexifix. It’s an extremely thiin film. I get the 4" rolls and cut a small strip for each side of the dexcom adhesive. The stuff lasts forever, through water, sweat, etc. I’ve had the entire dexcom adhesive lift, and the sensor last another week because the flexifix held so well.
I, too, had trouble hearing the alarm during the night. I have it set to vibrate and alarm, and sleep with it under my pillow. No way can it NOT wake you up!
Dig this. I called DexCom tech support to confirm what I already knew (as do we all)–there’s no volume setting on the DexCom. I did, however, get a suggestion couched in a stern “…this is not something we officially recommend…” disclaimer: Put the receiver in a water glass on a firm surface (dresser, night table, or in my case, window sill above the bed head), with the alarm set to both beep and vibrate. It is much louder vibrating the glass!
LOL I think I’ll keep it under my pillow rather than risking broken glass. I have a feeling my terriers would consider it a chase-able object!
This a good and valid question badly answered in the supplied documentation.
first off, the most accurate readings of ones blood is at fingertips. Next, Dexcom sensor depending where it is positioned
will provide readings differently than those of ones fingers. You will get accurate readings of the glucose of the sensor location which will vary from fingertips.
Sensor location is another factor. For me arms were best and abdomen useless. Many times on gut I would wake up with 160 on gut and fingertips - 230. Arm never showed such variance. I am unclear who idiot was who decided gut best. On another web site I found users who stated emphatically that gut useless and arms and other locations better.
Another factor not discussed is how fast does your BG shift around. If it is slowly moving like waves on placid lake, sensor on interstitial tissue will track much better than if your BG numbers move a lot and quickly.
i was on wrong insulin 75/25 that was booting my bg rail to rail and on slight exercise. Now on humalog lispro and no pills such as starlix/glyburide; BG far more stable and performance of Dexcom vastly better. Frequency response and data not given by dexcom and frankly they were unhelpful.
generally, interstitial tissues track slower than fingertips and result in differences of readings and slow tracking.
also, i typically find most times, dexcom agrees with freestyle lite meter within +/- 10 units except on change where the dexcom has to catch up. When sensor is getting to end of use, i usually see larger differences and extra changes in readings even though handheld is stable.
accuracy numbers stated from dexcom are unhelpful and industry should be shot over its
+/- 20 per cent excuse making.
today i am happier but through my own efforts and website such as this… good luck
i also agree that first day on new sensor readings off and not helpful. I find by end of 10 hours tracking improves greatly.
Why not leave Obama and politics out of this? The FDA has always been poor in this respect. That is what happens when an important organization is perpetually underfunded and not particularly well staffed with highly qualified people. Nobody is likely to fix this and doing away with the FDA is even more dangerous. Let’s stick to the Dex.
Jeff
“If the sensor is off by 100% up or 50% down (particularly more than once), call Dexcom and get a (free) replacement.”
Really? Dexcom has this sort of policy? I thought they only do the once that give “Sensor failed” messages?
Another question regarding this Dexcom replacement policy. (I live in Europe currently). Do they want to have the old sensors back and the data before they give you refund in US?