I’ve been using the dex for a few months. The first couple of times I would actually take two separate bg readings and enter them. Now I just take one and enter it twice. Seems like the dex’s accuracy is the same no matter which I do.
Also when I first got the dex the trainer suggested that people don’t test twice. So I don’t feel too bad about not doing it. What are other people doing?
yes, yes! 
And use different finger. I also do each hand to make sure I get a balanced reading!
per the training i got, i always test once and enter it in twice.
My son uses both hands - and does two readings.
HI. I always test twice (one poke, two strips).and enter both readings.
I would tend to agree that as long as the BG number you enter is representative of BG, it should not affect the accuracy.
Would you be doing so only to save on one strip?
Timing of your post is funny because for the first time ever today both of my start up readings were the exact same number (181–two hours after breakfast).
The training I got from my CDE, who is also has diabetes said always use two different fingers, because you will get two different readings which is better for sensor accuracy. This morning mine was 100 and 104. However, I can’t find anything in the book that gives clear recommendation for the separate fingers, but my diabetes team (doc and CDE) said use different fingers.
I’ve always wondered about the need to enter two readings, and my view is that by entering two readings in a row we’re just “telling” the Dexcom to disregard the previous calibration history and start with a new profile due to a new (or not-so-new) sensor.
Infact, sometimes I enter the BG reding twice even in normal operations, particularly so when what I read on the Dexcom is very different from my BG reading.
I’ve never pricked my finger twice, and used two strips to read BG in order to do the initial calibration. No need to waste consumables, and the fingerstick reading have errors too!
Ciao, Luca
I test twice, once from each hand. Surprised by how much the two numbers can vary, but I suppose that has more to do with meter accuracy than with the actual glucose levels I have. Still - seems like a good practice. Usually takes a good 18 to 32 hours of calibration negotiations between my Dexcom and me before things start reading the same.
Most of the time, I do two tests - because if I don’t, it will be one of those times where my test was off because the alcohol on my finger wasn’t dry enough, etc., and then I’ve calibrated the CGM wrong.
I decided to look up calibrate:
cal·i·brate
1 : to ascertain the caliber of (as a thermometer tube)
2 : to determine, rectify, or mark the graduations of (as a thermometer tube)
3 : to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors
4 : to adjust precisely for a particular function
5 : to measure precisely; especially : to measure against a standard
courtesy of merriam-webster.com
one CAREFUL test, entered twice.
But in contrast, I feel that waiting an entire 12 hours before re-calibration is a mistake. (On a new Sensor; not the 2nd or 3rd week of an old one.) Things change a lot during those first few hours, so I try to do some extra ones.
I like to do it twice on separate fingers just to be sure the first wasn’t the result of lotion or sugar being on the first finger thus messing up the initial accuracy.
I almost always test twice (one poke, two strips, as Scott put it). I was initially surprised that the two readings sometimes differed by 5-10%. I see it as giving Dexcom the average of the two.
PaulG,
I understand the FDA only requires FS BGs to be +/- 30%. I understand this to mean if my real BG is 100 the FS can be 70-130. My reading of the Dexcom internal mathematics is it takes this statistical range into effect.
My endo is also a university research endo. My endo, the Dexcom rep, and the endo’s CDE and I agreed one poke, two strips and if the spread was greater than 30% of the average, then a third strip. Enter all three values.
For SAFETY, use two strips. If you read off - say -30%, enter it, then start some mild activity, you may bottom faster than you expected.
Jay
Not only at startup but for every calibration I use one poke and 2 strips. If the 2 values are not close enough I use a tie-breaker strip.
You’re funny, Helmut! You make it sound like a game show (“Time now for the tie-breaker round…”).
Etta, thanks for giving me credit for my language handicap.
(In reply to Jay):
This is not exactly what the FDA “requires”. Any sample-based measurement technology has a non-zero probability of being VASTLY wrong – so they think in terms of ‘confidence intervals’, ‘standard deviation’ and so on. But bG test strips have a couple of other testing issues, too:
(1) They’re much more “accurate, reliable” when measuring high bG levels (e.g., 250 mg/dL) than they are at measuring low bG levels (e.g., 40 mg/dL). If you’ve done the test carefully, AND your strips have been stored well, AND you’re using a high-quality product, then you can expect a standard deviation of only a couple percent on a large number of tests done from the same blood sample. But at 40 mg/dL, even a lot of the good brands will throw out numbers with a lot of variability (25, then 55, then 42, then 61… all over the place.)
(2) FDA has approved several products which, IMO, simply don’t have the accuracy/reliability you need. (IMO, you can’t rely on ‘Reli-On’.) As you probably know, they are studying whether to require higher standards. I don’t know if they are especially concerned with a dangerous lack of accuracy in the Hypo range – but I hope that they are.
(3) Some products can also perform “well” under a very limited range of temperature or altitude conditions. If your strips don’t document their performance across the temperature range you need, then change brands. (I use good old One-Touch Ultra, because they’re good over an extremely wide range of temperatures.)
So, if I do two tests from the same bottle of strips, using the same blood sample, I’ll usually see a difference of less than 3% at bG readings above 100 mg/dL. Between 70-100 mg/dL, I’ll see a wider spread, and below 70 mg/dL, the numbers diverge a lot. Whenever I don’t believe a reading, I retry with a DIFFERENT meter, and a DIFFERENT bottle of strips.
I always test twice, and it makes good sense to do so. It’s rare to obtain two BG readings in a row that are identical, and I’m sure the extra data (i.e., the two very likely different readings) make a difference in the calibration process.
the person who trained you should be chewed up!!! paulG and others are very right on this… you should call the trainer to stop “training” peeps this way.