Freestyle Libre 3+ sensor

@jcatoe I use a Dexcom G6 (and an Omnipod 5 insulin pump). I usually have these devices on my abdomen. I rotate them around from left to right and above my waist & below my waist. Sometimes I have used the backside of my upper arms, but that requires help from my husband. I have had times when the continual glucose monitor (CGM) and the glucose monitor were way off from each other. I contacted the customer service helpline. First they reiterated that a glucose meter tests blood sugar and a CGM tests interstitial fluid ; the CGM can take awhile to catch up to the glucose meter. They also said that the CGM is not accurate when the level is very high (over 300) or very low (less than 40). They further said to make sure to check the glucose meter whenever there is a site change. The Dexcom G6 has a 2 hour warm up period so I use the glucose meter during that timeframe. The customer service people also said there are ranges or percent differences that are acceptable between the two devices. Mine usually stay within 10 points of each other; except on site change days the difference can be much larger. My take away from all that was while having a CGM is helpful and convenient, when in doubt trust the glucose meter.

@jcatoe I forgot to mention, Welcome to Mayo Clinic Connect!

Thanks for the information. I use the Freestyle Libre 3+. They suggest putting it the back of my upper arm but that seems to give me a different result than my meter. My next blood work is scheduled for next week so I guess I will just hold off before I panic. I was going to change it to the side of my upper arm because that seems to be the more accurate results for me

My Libre 3+ is usually within just a few points (higher or lower) of my fingerstick readings with the glucose meter. Occasionally up to 10 points difference, but not as much as my old Libre 3. Haven't noticed any difference between back or side arm sensor placement. I've even used the fronts of my arms a few times -- being careful to avoid muscle, and aiming for the fattier areas.
Some batches may differ, just like different batches of strips -- so I try to alternate the sensor dates when possible.

I use Medtronic 780g. I used Dexcom at one time too. I find both of them were closer to my meter number when worn on my upper arm. Still, sometimes it gets off….who knows why. Most of the time, it’s the same or within a few points off. From what I read, no cgm is without variations. Still, it’s a great benefit for those monitoring their BG. When something seems off, I fingerstick to confirm.

I wear a Dexcom G7 for continuous blood sugar monitoring. I use a regular glucose meter to calibrate it when I first put it on, and then again every few days.

I’m using the Dexcom G7. There is a chart that gives an acceptable range. That percentage is 20% in one way or the other. Ex: if blood glucose from a finger stick is 100 the CGM is “in specs” if it reads 80-120. Seems like a large variance but that’s the way it is. One must also remember that a finger stick isn’t absolute either. It can vary if finger isn’t clean, or one needs to press hard to get a drop of blood for the glucose meter test. Fortunately with Dexcom they can be calibrated whereas the Libre cannot. Pressure on the sensor can cause compression lows as well. Lot of variables can be involved. Even with that I wouldn’t be without a CGM. It’s not an uncommon complaint with all CGM’s.

Is there a type 2 who uses pump and insulin injections? How does that work for you?

My Libre 3+ is often 30-40 points off. This is more likely at the beginning of the sensor (when there’s still inflammation at the injection site). It also seems to be more off at high readings (ie, it says 250 when I’m actually ~200). But seems to be further affected by placement location, hydration, etc. I’m also quite low body fat which I suspect is an additional issue. I found it quite frustrating but have learned to accept it. I doubt the Dexcom would be any better. Use the sensor for trends and to find foods to which you’re particularly sensitive.

The Libre 3+ gets its info from interstitial fluid, not your blood. It is generally a little behind the finger stick reading. Just throw this into your dosing amounts. I usually go by what the Libre says but if very high or low I double check with a finger stick.