Dexcom question

I started my first sensor today. Training said that the first 24 hours were not always accurate and to use your meter. I have done this, but is 30 points difference okay? I know that the sensor runs behind. I am getting low glucose alerts and my bg is 88. What about the alarms for the first 24 hours during the night? Thank you ahead of time.

For me Dexcom can be off by a lot. Sometimes 100 points. Especially on the first day and towards end-of-life. I trust Dexcom to the degree that I can predict the meter reading. For example, if Dexcom read 20 points too high the last time around and it reads 100 now, then I predict that the meter will read 80. If it really reads 80 then I consider Dexcom 100% accurate. As long as I am able to predict the next meter reading, I am fine. Trust any sensor only to the degree that it has earned your trust. Trust starts at zero and ends close to zero.


This is wise.

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Thank you Terry4 and Helmut for taking the time to reply. I think I am going to like having the Dexcom if I can ever figure out the technology. I bought an apple watch and I already have an i-phone. I want them to be able to show my bg as well. I am looking forward to once again swimming since the watch is waterproof. You guys know so much and I have learned so much from this site. Thank you.

I have a similar setup (iPhone 7 Plus, Dexcom G5 Mobile CGM, Apple 3 Watch with Cellular- ALL with the latest software versions). Unless I am missing something on the setup, at this time, I still need the iPhone as an interface for the values to show on the Apple Watch, and for some reason I need to refresh the data on the watch by clicking on the value, to synch the watch and the iPhone. Eventually, I think there is no need for the iPhone once they update the Apple iOS and Dexcom system. I may be wrong, but If you swim with the apple watch you will still likely need the iPhone.

More info to confirm that the data needs to synch between the iPhone and Apple Watch. The watch does not communicate directly with the Dexcom transmitter (yet).

I have the same set up (G5, iPhone 7, Series 2 Watch). I also had the problem of having to tap the Dexcom icon on the watch to “refresh” the data. This can be really annoying, especially when biking, since you need both hands to tap and refresh. I found an app, sugarmate, that will make the data refresh much quicker, without interaction. The app essentially creates a calendar event every 5 minutes with your BG reading from Dexcom. The calendar events update almost instantaneously on the watch face (as opposed to Dexcom’s own app). Sugarmate also has a really nice interface and multiple metrics (a1c, time in range, average, flux, etc) that update throughout the day. I find myself using it more than Dexcom’s app. Give it a try!

Thanks for this info T1Architect. Yes it is truly problematic if you need to use both hands and can not get data on the watch without manual refresh- both annoying and dangerous ( for me when biking, using power tools, yard work, driving). I will certainly check the sugarmate App .

With regards to Yeagen’s situation, I guess the iPhone is still needed if she wants to swim and get CGM data on the Apple Watch?

Unfortunately, yes, you still need the iPhone in close proximity to get readings. I know apple advertised “Core Bluetooth” a while ago which would allow the G5 transmitter to talk directly to the watch. So far, I have not seen an update from dexcom that allows for this new feature.

Depending on the size of the pool, you could theoretically have the phone close enough to the water to get readings on your watch while you swim. I’m not sure if water impacts the range of the bluetooth connection.

Thank you T1Architect and ramCmd for your replies. I may check out the sugarmate app. Rats, about needing the phone. Oh well. Tools like Dexcom will make life better I think.


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Well, I downloaded the sugarmate App and so far I really like it. The voice activated extensive food database (complete with the photos of food and nutritional info like carbs &fiber) with the exact carb count, is more than enough reason to keep and use it. It takes a while to get the system working on the Apple Watch as you need to configure your device with the app through your Apple ID. The 2 factor authentication makes the process secure. Best of all, the App is free!

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Hi there. I got diagnosed when I WAS 22 MONTHS OLD; i AM 50, sENSORS ARE VERY INACCURATE. yOU MUST CHECK BY FINGER STICKS. Sorry I know it sucks but diabetes is the way it is.

Sorry that sensors are not accurate for you. They are very accurate for me, but each person is different with different results.

I started with the early Sof-sensors from medtronic, which WERE very inaccurate, but still helpful. Each new generation of sensors, has gotten more and more accurate for many people.

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Thx for the info.  have used Enlite sensors with my 630G pump fromMedtronic–the arrows 3 up or down are totally inaccurate. What am I doing wrong?

This thread is about dexcom sensors. You can start a new topic for Enlites, or find an older one specific to enlites using search function.

In general, the more variation in your BGs will show what looks inaccurate due to the lag. Sensors are not directly reading blood, so they lag. So if your BG is rising after a meal, 30+ points every 5 minutes, your sensor reading will be lower and not show correct arrow for many minutes.

But other factors may impact the accuracy, specific to Enlites, for example the ISIG factor.

My goodness, you have a lilfetime of fighting the diabetes beast. My brother. Hats off to you for still fighting the battle. Thank you for answering. We all have to stick together.

Yeah; diabetes sucks. I feel nothing in my toes; have a lot of trouble walking. i hate it.