Calibrating -

any ideas as to why you need to put in 2 blood test results when starting a new dexcom?

i usually just put in one blood test result - twice! and it seems to work just fine!

thanks!

(that is, WHEN it works!)

probably just to ensure accuracy in case one reading is off for some reason, especially if you only input bg readings 2x a day for calibration. i do the same thing with inputing one result twice, unless the reading seems off i may check again just to be sure

Home BG meters are neither particularly accurate nor precise . The FDA only requires them be accurate to +/- 20% By using 2 independent samples, you may get some improvement in precision. By entering the same sample twice, you lose this capability.

If you cheat the system of the few chances it has to get a good idea of the true BG value, don't be surprised if it gives less accurate results.

People think a finger stick is magically accurate to 3 significant figures... IT IS NOT.
A value of 101 can be anywhere from near 80 to near 120. And even that is only required to be true 95% of the time... the other 5% it can be even further off! Furthermore, no ongoing quality checks are made by the FDA after the strip is approved.

http://www.stripsafely.com/strip/

http://en.wikipedia.org/wiki/Accuracy_and_precision

Today I calibrated a new sensor. First reading on the Freestyle meter was 99 the next from the same drop of blood was 120. Because I didn't believe this, I did a third and it was 121. I entered the first 2 values into the Dexcom and it came up with 108. In the greater scheme of things I need the Dex to catch the lows. The middle of the road stuff doesn't concern me.

You need to enter the 2 values... The Dexcom will take the 2 values and calculate an average on where to start and then it does its sensing from there. If you use the same value twice it can effect your sensor readings and cause swinging.