CGM for people with low body fat

I am interested in the idea of a CGM. However, when I was discussing it with a friend recently, the said they had a really hard time getting accurate readings on their Dexcom, and that they were told it was likely because they were quite thin and did not have enough fat for proper placement. This seemed really odd to me, since I would think one of the most important uses of CGM would be for athletes, who should have pretty high muscle and low fat.

I was just wondering if any of you had noticed issues with inaccurate CGM readings that could be due to low body fat. I don’t want to invest in one only to have it be really inaccurate (I know it can still be used for sensing trends, but for my friend, the numbers were REALLY off).

hi @cmanton, the matter is that CGM inaccuracies vary with people. There are many here that find the CGM too inaccurate to continue to use, others find it better, some find it great.

one thing to note, CGM accuracy generally decreases with physical activity, largely due to bigger differences between interstitial fluid (what the CGM is reading) and plasma blood glucose (what you really want to measure). So as far as an important use for athletes, it isn’t always so.

there’s no way to tell how accurate a brand of CGM will be with you, until you get one.

the need for solid calibration is another issue, and calibrations done when blood sugar is changing typically result in CGM readings very far from reality. When I calibrate mine, I typically skip a meal to ensure near flat blood sugar change - and then I get pretty good results.

anyway, hope you are one of the ones that it works great for, good luck!

I have the same problem. I’m just a normal healthy weight, but with very little fat in my tummy/abdomen area. My CDE even jokingly scolds me for being “too skinny” because the CGM doesn’t have many places to go. I have found two areas that have worked OK with my Enlite CGM: the back of my arms and the top of my thigh, just a little to the side from the front. Unfortunately I can’t reach the backs of my arms well by myself, so the thighs have been best for me. But not always - sometimes I hit muscle or a blood vessel and have to start over. CGM hasn’t worked great for me because of that, but when it works, it works well and is really nice to have. If I hit a bad spot, Minimed is great and will usually send you a new sensor, but you have to call it in and go through the whole rigmarole of how to calibrate, because they have to cover their bases every time. If I hear the calibration speech one more time I think I will barf. : )

I also have little body fat but I use my arms or my thighs and have great accuracy with my Dexcom. I can no longer use my stomach because of lipoatriphy. You also need to keep hydrated.

My 9 yr old son is VERY skinny and we use Dexcom and get very accurate reading and never bleeding sensors. We did have some issues where we were OVER calibrating, as the other poster mentioned you need to to the calibrations at level times, no up or down arrows and not TOO often, we were doing both wrong at first… We do dose insulin on it, always finger stick for that and sometimes blood meter is off more than Dexcom! We get about 10-14 days out of our sensor using a
tegaderm" film that we reapply every 5 days or so. We use arms,and love handle area so far. And you can not cover that transmitter with a bandage for long term either, that will mess up readings, as does tylenol. We love it.

I use the Dexcom and I am on the thin side. The best places for me are my arms and hips away from muscle. You will never regret getting a Dexcom. It is a tool that I cannot live without.


I have been using Dexcom for about 6 months now and although I have had some issues with it, the good still largely outweigh the bad. I am pretty fit and exercise 6-7 days a week so I do have issues with the adhesive, but I just use paper tape once it starts to lose its stick. My biggest issue with it is around the insertion time. As I said, I don’t have much fat on my abdomen so I sometimes hit muscle or bleed and have to start over, it also takes a few hours for mine to get used to me and read accurately. I sometimes get question marks (alert that it can’t read) and sometimes really whacky and drastic readings, BUT when it works IT IS AMAZING. I love it for when I’m sleeping and exercising!

I hope you are able to get it and that you love it! Best of luck!

I switched from Enlite to Dexcom and find the Dexcom far superior. I usually wear it in my upper thighs, slightly toward the inside so it is not on my lap. (vertically) I recently injured my right leg and am now wearing the dex on my waist, but it is not as accurate there. Haven’t tried my arms but many people use that area. I am thin and need some flesh.I was in the hospital for 5 days in Denver after a fall from dehydration and high altitude in Vail. It was extremely accurate in the hospital the whole time. Everyone has to find the best place for insertion.

Oh boy! What a topic!

Took off the Dex about 3 weeks ago and haven’t put it back on. Wildly inaccurate for me. Dex says because of my low BMI. Regardless of where I insert.

Any benefit outweighed by negatives. Specifically beeping alarm going off reading 55, test, and 80s! Far above the 20% allowed deviation (20% at 55 would be 45 or 65, not 85!) Kept me up night after night. BEEP BEEP BEEP. (Shut up, i am not low!) Better sleeping and frankly even better #'s now that I’m not wearing it!

Hope others have better luck. Just doesn’t work for me AND negatives outweigh positives, by a lot.

For high intensity exercise, I found the Dexcom G4 to be very inaccurate. Fifteen minutes into a bike ride, it would consistently start beeping like crazy telling me I was LOW (<40 mg/dL). Huh, I felt fine and was riding fast so how could that be possible, especially after eating a snack prior to starting the ride. I can definitely relate to Vhm1’s comment, “Shut up, I am not low!” A few times, I carried a BG meter and stopped to check and blood sugar was fine. About 20 min after finishing a ride, my Dexcom would consistently say I was running high and increasing. Not true when I checked with BG meter. So, I stopped taking it with me on bike rides. It does the same thing if I do a intense cardio workout on elliptical trainer at gym. However, I still use it for other activities like hiking or weight lifting at gym and seems to do OK.

Being on the thin side can cause some problems. Harder to find a comfortable site and sometimes get some bleeding. Let’s face it, it’s not a perfect device but it does pretty good 80-90% of the time. Check your blood sugar if you feel low, high, or normal and the CGM is telling you otherwise. I also check several times per day just to keep it calibrated.

I wear a Dexcom G4 Platinum (pediatric) sensor and am also on the thinner side. I have had my Dexcom for a little over a year now. I love it and honestly don’t know what I would do without it. I use it to help me decide how to better administer insulin for certain kinds of meals and also to catch lows before I get dangerously low. Before I got my sensor, I would not feel lows and by the time I tested I would be in the 40s and 50s… not good! The only time I ever don’t wear my sensor is when I am going to diabetes camp and only because then it is slightly a pain to keep in range.

When I first got Dex and began to use it I had only been diagnosed about a year and was thinner than I am now from trying to regain the weight I lost before diagnosis. I always put the Dex sensor in my stomach. Sometimes I would have readings that were wildly off, but I would just calibrate the sensor and move on. When I overused a site on one side of my stomach, my doc told me I couldn’t use that site for three months and I was in a little bit of a dilemma because I had never used a site for Dex besides my stomach and I couldn’t use the same site for weeks on end without creating major amounts of scar tissue. So, I explored to find a new site. I didn’t want to try using my arm for fear of hitting muscle. So I thought about another place with some fat like my stomach. I inserted Dex on my backside, right below my pants line. I had to play around with the placement of the Dex sensor so that it wasn’t too low that I sat on it, it wasn’t too far to the left, or too far to the right, and also not so high up that my pants were putting constant pressure on it causing compression lows.

I would recommend trying out some different sites to see which one works best for you. My backside and my stomach are my main two sites for Dex, and now I mainly use it on my backside instead of my stomach. Once I found a “sweet spot” or the best place to put it for me, I loved it because the sensor was more out of the way then on my stomach and I didn’t have as much constant worry of knocking it off or it getting caught on something. It also is not very noticeable through pants.

Hope this helps!!