After using the G6 for 4 years, which I loved and came to trust, I switched onto Dexcom ONE at Christmas as it’s funded by the National Health Service here in the UK.
I have had nothing but trouble with the ONE, mostly related to inaccurate sensors. I’m getting avergae MARDs of 30%. Can’t calibrate the ONE either.
Despite the cost, I’ve decided to give the G7 a try, and have just placed an order for a trial month’s supply.
Does anyone else have any views on the ONE?
Hello @Rod welcome to Type One Nation. I hope you get sone feedback on the ONE sensor. I think it is not available in the US but I did read it is designed as a lower cost and simpler sensor, and there is no calibration. I am going to try G7 as well in s few weeks. Good luck!
Hi Joe
Many thanks - nice to meet you.
It’s disapointing to think that Dexcom has delivered a device that is lower quality and less accurate just because it’s the version that the NHS here can prescribe, so effectively free of cost for patients. The sensors and transmitters are exactly the same as the G6, I suspect the only difference between the ONE and the G6 is the software in the app/reader.
Maybe someone from Dexcom can comment???
Hi @Rod as far as I can tell, the difference is the transmitter. It is a limited channel transmitter and will not accept a calibration. The software is close to the g6 software as far as reading values, but does not contain the calibration piece. It is very unlikely that it is just the software. It is lower cost but I think the point is an easier system. Many people get frustrated with Dexcom because they do not know how to calibrate it, doing do at times of changing blood sugar or very high blood sugar, resulting in even more error and inconsistency
I don’t think anyone working for Dexcom is here but you never know!
Hi @Joe . Yeah, we’ll probably nenver know. All I can tell you is that the G6 and ONE transmitters look exactly identical (apart from the label printed on them of course) same for the sensors. You might be right about the calibration argument, but then why is calibration available on the G6 and G7?
I put on a new ONE sensor this morning as it was still showing a MARD of over 30%. This new one has been on for about 12 hours now and it’s still 30% out, sometimes they get better after about 24 hours. So far, about 50% of the ONE sensors I’ve used have been so bad I’ve had to stop them. If I was cynical I might think that as the sensors go down the Dexcom production line, the poorer quality ones get a ONE stamped on them 
I trusted my G6 100% and hardly ever needed to prick my fingers, I miss that.
Cheers
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The press release says “Dexcom ONE shares the same innovative sensing hardware as Dexcom G6…”
There are some software differences like not connecting to a pump and no low soon alerts. This link has a comparison table.
Slightly more details and the product photo shows a G7 reader with the One/G6 sensors.
Dexcom ONE | Dexcom Healthcare Professionals.
MARD applies to a large set of values and is not the expected accuracy of the device. Does the NHS publish the standards devices are evaluated against in order to be approved? The US version for the G6 is here:
Pages 40-41. Key accuracy standards are:
(E) For all iCGM measurements from 70-180 mg/dL, the percentage of iCGM
measurements within +/-40% of the corresponding blood glucose value must be
calculated, and the lower one-sided 95% confidence bound must exceed 99%.
AND
(B) For all iCGM measurements from 70-180 mg/dL, the percentage of iCGM
measurements within +/-15% of the corresponding blood glucose value must be
calculated, and the lower one-sided 95% confidence bound must exceed 70%.
AND
a bunch of others I’m leaving out because this is already too long.
Translation:
70-180 mg/dL = approximately 3.9- 10 mmol/L
lower one-sided 95% confidence bound can be described as: If X is a 95% lower one-sided bound, this would indicate that 95% of the population is greater than X
Some readings can be way off, usually not lower than a blood glucose measurement, but over 10 days it will be close enough. Also remember your BGM has the same kind of range of accuracy.
All this to say you r might not be wrong. Dropping pump support suggests to me that Dexcom ONE is going to be less accurate than the G6 some of the time. I wonder if Dexcom is trying to sell sensors that don’t meet their G6 specs but do meet a slightly looser specification. Important to note this is pure speculation bordering on fantasy on my part.
Thanks, interesting stats.
My empirical view is that I used the G6 for 4 years and came to trust it completely. I hadly ever felt the need to calibrate, and I’d say about 1 in 20 sensors failed.
I tried the ONE for 3 months. 1 in 2 sensors were so innacurate (MARDs of 30%) that I had to stop using them. Couldn’t calibrate, so just lost all faith in CGM.
Been using a G7 for 3 days, had to fund it myself. What a revelation!! After a 30 minute warm up, the readings were within 5% of my AccuCheck Instant meter. After 12 hours, the readings are less that 0.1mmol apart. I’ve bought a month’s trial of G7, if there are no surprises I will buy a subscription. Even though it’s not funded by the NHS and I can’t really afford it, it’s worth it for better health and better wellbeing I think.
I’m very grateful to Dexcom for coming up with this technology, I do think they’ve done me a dis-service with the ONE though.
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I don’t know if anyone will find this interesting or helpful, but nerdabetic just posted a new video on his YouTube channel about the dexcom one.
https://m.youtube.com/watch?v=lpZh41lLNXU
Thanks - very interesting, and spot on correct
You can request a refund if the equipment is malfunctioning