Navigator CGM glucose meter reads different than One Touch glucose meters

So I woke this morning and my one touch ultra smart read 84. This is the first time I tested with the navigator, and it gave a glucose reading of 66 (these are finger stick numbers not cgm numbers on the CGM). I then tested like a half hour later, because they were inconsistent, and my ultra smart read 78, the ultra mini read 74, and the CGM read 63. Which one would you believe? To correct or to not correct?

Now I am questioning the ultra smart (that cost me $80) I have loved for the last year, but I am also questioning the Freestyle Navigator (that cost me $1400 out of pocket).

Since I started using the DexCom 7+ I sometimes test more than once. I would not be surprised if I tested 3 times in a row and the numbers were 78, 74 and 63. I actually consider this quite normal. For calibration purposes I would then pick 74.


Since I’ve never used a Navigator CGM, I can’t comment from direct experience. What I can tell you is some more general info that I’ve learned. I’ve been using the DexCom CGM for six months. I don’t ever treat a BG (low or high) based on a CGM number; I do a finger-stick BG then treat based on that number. If I suspect a bad finger-stick number then I wash my hands and test again.

Remember that the CGM reads interstitial fluid – a number that lags actual BG by 15 minutes or more. The CGM is more dependable for trend info – your BG direction and how fast things are changing.

If I saw finger stick readings of 78 and 74 and a CGM reading of 63, I would suspect that my BG was rising and expect the CGM to follow in the next 15 minutes or so. I would also take into consideration how much active insulin I had in my system and the time since I last ate. All BG readings need to be placed in context.

How long have you had the CGM? I’ve had a great experience with mine; my A1c number has dropped a full percentage point since I started. Good luck.


Terry is right. Your CGM can show you which way you are going but make dosing or food decisions on your One touch. If I have a sudden and extreme spike, my CGM can be way off. If I have a high reading on my CGM, I definitely test with my One Touch before dosing for correction. I don’t know anything about the Navigator but whenever I do a finger stick, I calibrate my CGM if there is a substantial difference. I’ve had a Dexcom for more that a year now. Love the CGM technology.

The thing is that I checked it right when I got up, and then a half hour later. The numbers were still off by over 10 points. It wasn’t a CGM reading. It was a blood sugar test with a strip using the Navigator’s integrated blood glucose meter that was off by more than 10% from the other meter.

It says 68 now and the ultra smart one says 76 which isn’t as bad, but which meter do you trust?

I have to drive, so I am going to err on the side of caution and assume the 68 is right, but I am wondering for future reference. Do I have to double check the integrated meter on the Navigator?

I did to a control test for both meters / stips, so that is not the problem.

I 100% agree with ALL of Terry’s statements here.

If I understand you correctly, you were doing a finger stick using the freestyle that’s built into the navi right? If it was just that you were reading the CGM portion of the navi, then I would agree w/ what some of the others had said. If it was a finger stick, then I would go w/ the finger stick from the freestyle portion of the navi. That meter is built on a platform from the old Therasense company (googling that will bring you to Abbott, who bought out that meter) and it uses a technique known as coulometry that tests more accurately than many other meters on the market (this is my opinion, but there are research studies out there that will help verify that perspective). If you notice the time it takes to actually test the blood, the navi takes a few seconds longer most of the time, b/c it’s using that technology to get a more accurate reading than many of the other meters…that’s not to say the other meters are “bad”, but when I really need a number to “count on”, I use the navi’s freestyle meter.


So you would trust a fingerstick with the navigator more than the finger stick with the onetouch ultra smart?

It was not a CGM reading of 63. It was a finger stick number of 63 using the Navigator integrated glucose meter.

I faced a similar question: Which meter should I use? I have used One Touch Ultra for the last 10 years and was comfortable with it. My new OmniPod PDM has a built-in FreeStyle meter. Yesterday I used my last One Touch Ultra strip and switched over to FreeStyle. So far I like FreeStyle better. One Touch required gobs of blood. FreeStyle is happy with a speck. The first 2 measurements in a row were 101 and 102. I take this as a good sign. Time will tell.

Yeah Tanya, I’d trust a navigator finger stick :slight_smile: