Is Dexcom G4 CGM medically useful?

As we passed our one year anniversary, my son was still resistant to adding a second device - the Dexcom CGM - because new devices are a bit overwhelming for him still.

I thought that fewer manual blood glucose tests would be appealing enough to get him started on the CGM and relieve some of his concerns about highs and lows, especially now that his new orders are demanding more tests which are very disruptive to his school day.

The bad news from our physician is that he still wants to require manual blood glucose testing – even with the CGM --every time a correction is made, and not just twice a day for calibration, which would actually increase our manual BG tests by two per day.

He was crestfallen when we got this news from the doctor and I’m not looking forward to returning the Dexcom.

If we can’t trust the Dexcom’s accuracy, how is it still on the market being sold with these claims?

Is the Dexcom CGM medically useful?!?

One word: YES


There is nothing (besides insulin) that I would give up over my Dexcom. It is an essential tool in the belt for me. It’s absolutely 100% medically useful.


Calibrating 2X/day doesn’t have to add more fingersticks. Calibrate when you do the pre-meal checks at breakfast & dinner.

There are plenty of G4 users who find the accuracy good enough to bolus from, although not always. With time & experience you learn when to trust a sensor.

I guess I don’t understand how checking BG can be so disruptive to school. Does your son check in class on his own or is he required to go to the nurse? My daughter was dxd at 11 & stopped going to the nurse for BG checks 3 months after dx. I just didn’t see any reason for her to miss class.

Reducing the number of fingersticks per day is near the bottom of my reasons for Dexcom’s usefulness.


You would be crazy to give up the Dexcom IMO. It’s the BEST thing I ever did for my diabetes. And they say you can’t officially dose off of it but if you’ll read the FDA recommended to be allowed to dose off it but I think it’s just not approved officially. My G5 is always right in the money with my meter unless I’m having a low then I know I need to check my meter, but my meter is always LOWER than my Dexcom due to the lag.

The main thing the Dexcom gives you is the trend graph to proactively let you know if it’s stable or going up or down.

I’m pretty sure most people dose off it and it’s been extremely accurate for me. But don’t do it for the first 24 hours!



Thanks for your post. Are you saying the first 24 hours of each sensor or when we’ve first started using the device?

Thanks for all your feedback!

I’ll try to be a better cheerleader with my son and see if we can’t get things going. He doesn’t like his nurse interactions at school which he finds stressful as well as disruptive. This is the issue.

I concur with the previous responses. The CGM is highly useful. It allows you to treat diabetes in a dynamic rather than static way. Adding insulin or glucose in a timely way makes all the difference.

It is entirely medically useful. I will go one step further; I consider the CGM as an essential and crucial safety device for living with diabetes. It has saved my bacon many times.


Now I’m hungry for bacon



You hit the nail on the head. Be supportive and most importantly, patience is the key with the Dexcom. Once you and your son start to figure out the nuances it will become invaluable for him as well.

Good luck

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First 24 hours of each sensor. I’ve never had a problem even in the first 24 hours but I’ve read that it’s not stable until 24 hours.

I consider my Dexcom essential. Even though my insurance company bailed out on me, I am still keeping it and paying out of pocket.

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The acclimation of a sensor is due to its “wetting” itself. One thing that I have started doing recently is inserting a sensor the night before I activate it. I keep the old sensor going so that I am not totally BG blind. I insert the new sensor and then use an old-expired “dummy” transmitter to protect it from damage. Then the next day I end the old sensor. I remove the dummy transmitter from the new sensor and start the sensor with the active transmitter. This definitely shortens the start-up issues with a new sensor.


Good idea!

I would say YES. I am paying for my Dexcom out of pocket, and it’s worth the cost (otherwise I wouldn’t be doing it!). I wouldn’t be exaggerating to say that it’s changed my life in terms of diabetes management.

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Sorry, I just got the Dexcom G4 last month. I don’t understand how you switch out the transmitters? I’ve actually messed up inserting sensors because I accidentally broke off the plastic piece towards the bottom and could no longer get the transmitter in.

I’ve broken off that little lever before I’ve inserted the transmitter onto the sensor mount. You can still insert the transmitter without the lever. I’ve just used a lot of force applied with my thumb and clicked it into place. It is possible and I worried about disturbing the sensor when I pressed hard on the transmitter but it worked out OK.

Where is your sensor mounted? Can you see it easily?

I agree with @Terry4, you don’t really need that plastic bit to get the transmitter in. If you hook your finger just under each corner of the back end of the sensor (it’s the side that’s not attached directly to the adhesive, so you can get a finger underneath and lift very slightly without pulling anything off), then it’s pretty easy to press down from the top with another finger and click the two sides into place.

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I have it in my stomach, but have to change it sooner than later. Sounds like force got it into place, but you mentioned that your transmitter still worked ok. I will try playing around with it tonight and see how it goes.

Thank you!!!


Thank you also! Your directions are a little more descriptive and that helps a lot.

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