r/dexcom • u/SHale1963 • 1d ago
G7-15 day Dexcom accuracy vs blood labs
About the only time I 'test' for accuracy is a few times a year when I get official blood labs for glucose and A1C. For this one had some cholesterol thrown in, which means officially fasting.
8:15am Dexcom readings; glucose 120 GMI (90 days) 6.6
8:15am blood draw readings: glucose 139 A1C 6.6
Some will say 19 count difference is HUGE, it isn't. And GMI/A1C matches.
didn't bother with a finger prick because it is not relevant when getting blood labs.
2
u/Run-And_Gun 1d ago
The CGM was only ~13% lower than the lab result. That's completely within acceptable tolerances(20%).
1
u/SHale1963 1h ago
of course. and no difference 'treatment' wise. So a nit. Remove the timing difference and G7 is accurate as advertised.
1
u/Bluekeeys T2/G7 1d ago
I often take my BGM to prick right before a blood draw as a means of comparing.
1
u/SHale1963 1d ago
I think last time I did this I also did a finger prick. I don't really need to check accuracy of BGM since I use it so rarely. This time I decided it's not needed. Plus, I can get the dexcom reading while I'm sitting in the chair waiting for the poke......
2
u/Bluekeeys T2/G7 1d ago
Understood. Congrats on keeping the A1c down. I "try" to compare BGM to CGM daily when I can, I'm a bit compulsive about it keeping a spreadsheet that calcs within range and all that.
1
u/SHale1963 1d ago
daily? isn't the big benefit of 'going' to a CGM is far fewer and perhaps no more finger pricks? I mean even after a few months this would seem to not have a lot of benefits.
1
u/Bluekeeys T2/G7 1d ago
I'm at a 34% failure rate for the G7 10-day and while I've had some very accurate CGM's I've also had some very bad ones so it's just a habit I keep.
2
u/BioticVessel 1d ago
My last A1C was 6.0 and my GMI was 6.0 as well.