New to G6 with BG readings very high

I just got my G6 update on Medicare and my BG is crazy. I usually run fasting of less than 100 and these first few days have been 150-180??? My nasals, boluses, and diet have not changed from the G5. Has anyone else had this issue?

Have you double checked with finger sticks?

Its a new device. I’m with Willow4.

I just put on my first sensor yesterday and at 2am I had to take the receiver and my phone out of range to stop the incessant low alarms. By finger stick and a Libre (I’m overlapping a few days just to see) the dexcom is 40-50 points lower than actual.

Another vote to finger stick. :slight_smile:

@Patricecape - Are you well hydrated?

Try drinking 24-36 oz of water a day, most of it early on

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Thanks all for your input. I am never overly hydrated, as in the 8 glasses a day, but I Usually reach 4-5.but I know I should drink more.
Yes I am still checking my old monitor, and it matches what my old numbers were, which is around 50 points lower than G6. That really bugs me with the fasting numbers, but it seems odd to make adjustments in my overnight basal because my BG has always been flat overnight and 90-115 fasting.
So, I don’t know whether to treat for the G6 or the finger stick.? I figure since I’m not supposed to be checking finger sticks unless I feel differently than what the G6 reads, than I should go with the G6. However, I don’t usually feel symptoms at all unless >300 ( which I never am) or < 55. :frowning:

You can calibrate the g6 if it is so far removed from your finger stick tester. Try calibrating but only when the arrow is steady and BG is neither rising nor falling.


Thanks. I’ll try that method.

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Best to follow your instincts, not the dexcom rules in this case. Assume you have accurate bg meter that aligns with A1C. Gradually you will learn when to trust bg meter over G6, and when to calibrate or not, based on your meter BG.

Hydration is important, but so are many other factors. Location you put sensor may give better readings. Or for you, day 1 and 2 need more time to settle in.

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I didn’t like the G6 when I first got it. Now I love it and trust it completely for making decisions unless the numbers don’t match how I feel. Two changes made the difference for me -

  1. Presoak the sensor to avoid the insane readings on day 1 (and for some people, day 2). The process is simple. Insert a new sensor 12-24 hours before the current sensor expires. When it does, move the transmitter to the one that’s been ‘soaking’ and start a new session. The sensor is equilibrated and for most people it is stable and accurate right from the start (sometimes reads high for about two hours. Then falls in line with finger stick).

  2. use very light pressure between the inserter and your skin. Push the inserter down until the adhesive just barely touches the skin, pull the trigger. Then push the inserter down fully to seat the adhesive.

I was ready to bag the G6 until I found these methods. Good luck!


I am on my second G6 sensor and it is only my opinion that sensors themselves can be different depending on where on your body you place them. I also have been on Dexcom since 2007 and I always check my blood glucose if it is a LOT different that what Dexcom receiver says. Somewhere on Dexcom manual, I read - “when in doubt, get your meter out.” Best wishes to you and be safe.


You are seeing sensor inaccuracy.

Lets talk more about calibration and how much error you are seeing.
50 points of difference will make calibration difficult - expect to loose sensor data for some period.

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I can’t quite tell from what you’ve said so far, but it’s a pretty established fact that all sensors can be flaky in the first 12-24hrs, and I’ve found that to be more so in the case of G6 than G5. As @Paytone says, there are a couple of things you can do to ameliorate this effect. Pre-soaking has really helped me. In my case, 12 hours seems to do the trick, but 24 is best if you can manage it. FWIW right from the start I’ve found the G6 to be far more accurate than any other CGM I’ve tried (Medtronic Guardian 3 included) and I am currently down to fingerstick testing only once a day, just to check that I’m on track, unless I see something that really looks out of whack, which is rare. Not everyone has the same experience of course, and it’s possible to get a bad sensor, but I’d give it a solid try before deciding it doesn’t work for you.


Just as a note - Do as I say, not as I do. Sigh.

I just dosed off my sensor BG = 250 (and I recognized that predicted dose was crazy - 14 units, when it should have been around 4, but I delivered it anyway).

Then, I did a manual stick and it was BG = 180. So, I should have delivered 2u. I delivered an excess of 12u. I am an idiot.

Here comes trouble…


Wow! I hope you are alright!


I learned my lesson, I think.
Loop has a really long insulin tail. I was low for 6 hours.
But, a handful of sugar sodas later, I survived to dose off my sensor another day.
I’m just wearing an expired one. Data is more trouble than its worth, LOL.


Glad to hear that you made it through! I was a bit worried about you.

Loop exposes us to a better understanding of just how long the tail is. After all, the insulin hasn’t changed.

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Yea, 6 hours. Makes calculations kinda hard because there’s almost no discernible time when there is not insulin active, to some degree. Not sure how to account for that yet in bolus testing.

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I have learned a lot from the responses to my post. I had never heard of pre-soaking, and the sensor insertion method. I am very thin, so I will surely give that a try.
However, I think I was just over reacting because the G6 was new to me. After a couple of days it all ok and within 10 points of glucometer.
I started the second sensor yesterday and forgot to put the number from the sensor in, and I didn’t realise it would disappear from the adhesive cover when you remove it. Oddly, that number doesn’t seem to be anywhere else on the sensor box, so I am back to calibrating for 10 days. Oh well…live and learn.:nerd_face:

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Great! Glad things are working out.

I made the same mistake with my first sensor and ended up digging through the trash to find it. Now I take a picture of the inserter before I use it.