Dexcom G7 CGM usage

I used to use Dexcom years ago and now use Medtronic Guardian 3, 4 and later Instinct sensors. I’ve researched many of them and Imo all cgms have pros and cons.

A discrepancy between the cgm and a finger stick is rather common. I try not to get too bothered by it. Usually, they will get closer. The cgm is about 15 minutes behind the blood figure. You can read a lot about why having variations are pretty expected. However, my experiences have been that often my numbers are very close. Figuring out why….is difficult. You can try a few things if the numbers are consistently off. I moved my cgm site to my upper arms rather than my torso and that worked much better. There’s also the possibility of sensors being defective. You can call Dexcom and report it and ask for instructions and replacements if necessary.

I try not to finger stick too much due to the kind of sensor I have. Only if my cgm is saying I’m very low or very high. If your BG is actually going up very high and then going very low, I’d discuss with your endo or their office staff. Perhaps there is an insulin dosing issue like insulin/carb ratio, basal amounts, etc. that isn’t really a cgm issue.

Some people switch to a different cgm. I’d research several first. Most have some complaints about accuracy. I think we assume the blood meter is more accurate than the cgm, but can we be sure?

Ref. Adhesive..you might try Skin tac which is applied underneath the adhesive and protects the skin and there are wipes of adhesive remover. On line diabetes supply sites should carry them.

I hope you get some more responses. The online diabetes community often involves complaints and support for CGM performance. I am glad to say they have improved tremendously over the last 10 years.

Dexcom user here since the G5 and currently using the G7 10 day sensor. celia16 comments are valid. A great feature of Dexcom CGM's is they can be calibrated unlike some other CGM's. Best calibration technique is to have a horizontal arrow➡️ for the last 15 minutes, meaning your glucose is stable. Glucose meters are not 100% accurate either. Some people will take the average of 3 finger stick readings and use that number to calibrate the CGM. This will link you to the Dexcom calibration chart: (It's labeled G6 but it's the same for the G7). https://cdn.media.amplience.net/i/dexcom/en-us-g6-meter-g6-comparison-table

Seems like 20% is a large variation for being in spec but that is what it is. Also note that CGM manufacturers all say that if the reading you see doesn't match the way you feel, e.g. CGM reads 115 and you sweaty, shaky, signs you are low, do a finger stick to verify the reading.

First 12-24 hours of a new CGM insertion, the readings can be a little woky. Your body reacting to a new object invasion, trauma in healing the wound and who knows what all, until the body settles down. If readings are off by 40%, I would calibrate it during the first 24 hours. For your comfort, do a finger stick occasionally, compare it to the chart and calibrate if needed.

Recommended placement of the CGM is the upper back of the arms. I get good readings there but I need the G7 to talk to my pump and best communication is accomplished when the two are in line of sight with each other. Holds true for your phone, or receiver as well. Don't be afraid to try other locations. Abdomen, upper chest, lower back, thighs are used. The interstitial fluid is all over your body. Also prolong pressure on the sensor, like laying on it when sleeping, will cause a sharp drop in the reading and may trigger a low glucose alert. It's a pain at night I know, don't panic and down glucose tables, or juice as the first thought. Look at the glucose reading chart on your phone or receiver and see if it did drop off suddenly. If in doubt, do a finger stick. That panic glucose treatment will just result in a high spike within 20 minutes or so and then you have to deal with that.

If you discover the sensor is flaky, call Dexcom. They have always replace "faulty" sensors even when the sensor is not on the back of the arm as recommended. A flat out sensor failure, rare for me, a form can be filled out on-line or in the Dexcom sensor app on your phone, to get a replacement.

I'd consider yourself fortunate that the sensor stays on so securely to your skin. Way better then it falling off early as some users experience. I too, need to literally rid it off. celia16's suggestions for removal are good.

Last bit of wisdom I'll pass on: Diabetes does not play by any rules. The same food intake with same insulin dosage that worked for several days with nice glucose readings, can cause a crash or high readings the next. It is said that there are 50+ variables that affect glucose levels. Some known to you (miscounted for the lasagna) and many you have no idea why, even the weather. And it is worse for women. Give yourself some grace. It's the prolonged uncontrolled highs that cause the harm. Of course, the window for lows are more urgent to deal with. All insulin dependent diabetics have bad days, and don't let anyone tell you otherwise. Keeping the numbers between the lines is the destination. It's figuring out the path, that constantly is changing, is the challenge. Day at a time. Good luck to you.

@drlundeen ,good points.

I agree and so appreciate drlundeen’s reply! Especially about recalibration during the first 24 hours of a new Dexcom G7 sensor and that diabetes changes over time for women

I’ve called Dexcom several times when my G7 has been faulty. It usually happens in the first 24 hours of applying a new sensor that it either doesn’t “pair” or it stops working all together. The readings are all usually low by 30-80 points of my finger stick. They ask me a few questions and then mail me a replacement sensor.

And I also appreciated the “last bit of wisdom” = diabetes doesn’t play by any rules!

I saw a definite change when I was in pre menopause and now in post menopause. Not fun to have severe menopause symptoms AND diabetes fluctuations.

For me it’s a full time job managing my low carbs, high protein, exercise, meds, supplements, stress, sleep, CGM, finger sticks to verify CGM readings and doctor appointments.

I must admit I didn’t take my type 2 diabetes seriously when I was diagnosed in 2005. I wish I had done more research back then like I’m doing now. It wasn’t until 2019 that I finally connected with a proactive endocrinologist and saw progress. Even then I found I couldn’t count on her to do all the research it takes to get the answers I needed for my “snowflake”/unique genetic health problems = PCOS, Metabolic Syndrome, diabetes, high blood pressure and high cholesterol.

Bottom line: I encourage you to find out what is causing your drastic lows and high readings into the 300s.

I’m type 2 diabetic using Dexcom G7, so I can’t speak to what is causing your type 1 diabetic Dexcom G7 fluctuations.

When my readings were in the 300s it was due to high carbs and/or stress. Now I’ve learned to manage my food intake and stress.

Full disclosure - for 8 months I’ve used Mounjaro and lost 30 pounds. I’m also using the Carb Manager app on my phone to keep track of my macros. And my new nurse practitioner endocrinologist recommended 2 supplements which also seem to be helping steady my blood sugar AND lose weight = dihydo-berberine and alpha lipoic acid.

So much new technology and information out there. Just need to keep looking and trying.

50+ years diabetic. I use a Dexcom G7 15 day CGM and an Omnipod G5 pump.
I too see discrepancies in readings especially on sensor change days. It used to be for 24 - 72 hours which I thought was unacceptable! It is getting better maybe 8 - 24 hours, thank God!
Whenever I question the CGM data I see, I do a finger stick with the meter. If there’s a big discrepancy, I calibrate the CGM. Thankfully this isn’t necessary a lot!
Regarding the stickiness of CGM’s. Better stuck than falling off (early). On sensor change days I use a product called UNI-SOLVE. They are individual foil packets of swabs. I saturate the area with one before I try to peel it off. That has helped a lot. I found them at the local pharmacy but I’m pretty sure Amazon has them for cheap. Don’t they have everything?

I love my Dexcom G7 ... I'm about to transition to G7 15 ... they are extending the life of the sensor from 10 days
to 15 days. They want you to calibrate your sensor with the finger test. My one touch wasn't too accurate ... I could get my finer sticks to wildly swing just two minutes a part (250 to 125); in the past, I thought the finder sticks were gospel. It turns out they can be wildly different. Medicare wanted to to change to Libre (Free Style); these devices / test strips are much more accurate. I thought all finger strip tests were inaccurate. I've found the Dexcom monitoring devices to be extremely accurate. If they seem to be testing high for my food intake, it is usually driven by the flu or an infection that I was experiencing. I think you'll find the Dexcom system really helpful in managing your diabetes ... you can see how foods affect your blood sugars and how quickly. It has helped me eliminate some foods (ie rice) from my recipes. I didn't have a good handle on my A1C prior to Dexcom, but over the past 5 years I've kept it below 7.0. Since I'be been on medicare, they gave me the benefit of getting 5 lucnhes/ 5 Dinners designed for diabetics. They do all of the menus and deliver the groceries on a weekly basis for 17 weeks. It ws an eye-opener for me. My meals for the day were limited to 1,500 calories. I don't eat breakfast so it wasn't hard to follow. Plus the menus varied on a day to day basis. The portions are big enough that I don't feel hungry. I've lost 25 pounds over 5 months. After going thru the 17 wife and I go thru the meal plans & pick the ones I like best. I was thinking of going through a food delivery service (many good ones out there --- just look thru google) & they aren't to expensive. I'm pretty thankful for the Dexcom system as well as the medicare foodservice for diabetics. I have positive momentum in my life. My endricanoligist at UCLA ... I would totally recommend her as well.

My Freestyle Libre usually reads within just a few points of fingerstick. Sometimes more when recently inserted. I have type 2, on insulin, and it's a big help.

@davidyapp , that sounds great! I use Medtronic, but what is the name of the program in Medicare that provides the free healthy meals?

the program is only for people who have diabetes -- it is part of the UCLA Health Medicare Advantage Prestige Plan (HMO) --- Benefits for the chronically ill (must have one of the following chronic conditions Kidney Dialysis, Heart Failure, or Diabetes. The patient has to fill out a Health Risk Assessment. If you qualif, you get 13 weeks of meals (lunch/dinner) for 5 days a week. They help you build weekly meal plan supporting your chronic condition
and drop off groceries supporting the weekly meal plan. It was a great benefit for me as I retired 5 months ago & my wife & I used to pick-up fast-food on the way home from work. I've learned a lot from meal planning from this program and it was a great way to kick-off retirement ... I've lost 25 pounds during the 5 months. I aways thought a diabetic meal plan would be starvation ... but it isn't. Good luck to you. David

@davidyapp , sounds great! And congratulations on your success ! Sounds like a great program!

I have a Humana Supplement plan, so…..idk. I’ll check it out. I have type 1 diabetes. I’ve lost a lot of weight on my own with meal plans I developed and fine tuned with nutritionists at my endocrinologist’s office. I would love to participate in the program though. Thanks for the tip!