Frequency of fingersticks - pre and post CGM

Diabetes Technology Glucose Monitoring
1

My 12 year old daughter just finished her 1st week using the Dexcom G4, and we all love it! (She also is a pumper of 8 years, currently using the Animus Ping)

Being new to the CGM world, we are curious about how frequently CGM users test with their meter now vs. when they had no CGM.

I recall one visit to the endo where the staff told our daughter that having a CGM would mean less fingersticks (which I think we all can appreciate as a welcome relief.) It seems that the notion was propagated that my girl would only need to test 2x/day (calibrations) and to validate extreme low or highs.

She has been making corrections based upon the Dexcom reading, and I have to say, her BG control has been great and all of the CGM data has enabled fine tuning of her basal.

My Questions Are These:
1) based upon real world use of CGM (and of the Dexcom G4 in particular) what is (your) actual rate of fingerstick checks while using the CGM?

2) How much confidence do CGM users have in making corrections based upon CGM numbers?

3) If and when a CGM fails, what has (or have) been the obvious failure signs?

I fully understand the manufacture's stance; I am asking for candid answers from diabetics with experience using CGM.

Your honest input is greatly appreciated. Thanks so much.

2

1) I still test around 8-12x day, which is probably close to the amount I tested before I had the CGM. I use the Medtronic sensors, still the old ones and, while I get good results with it, like to keep an eye on it.

2) I am pretty confident in mine but generally like to check to make sure.

3) if it's reading off regularly, I have called Medtronic and they've gone "you're under warranty, it's time for a new one..." and sent it out.

3

1). After I started to use a CGM I doubled my finger sticks, I have been using a CGMS for over 6 years now.

2). I do corrections and bolus for meals during the day without doing a finger stick and correct on the fly but I calibrate 3 times a day and my average is 7 test strips a day.

3). I change my Sensor every 7 days and have very good results, My meter average when compared to SG average is around 3%. I would say the biggest problem with SG is lag time and occasional flat line at night or during times when my activity is low. Time of use and experience are your best defense against false readings. The obvious failure sign is when your meter says your sensor is off by an unacceptable amount. (just like a meter reading, experience tells you that "that reading cannot be right"?...and you retest to find a 50+ point difference)...experience, experience, experience.

There's no crystal ball, some individuals are very good at their BG management others are really bad and most fit somewhere in between these to extremes. A CGMS will make life easier for you but it does not diminish your amount of work, in fact it probably will add to your daily chores...but the pay off is well worth the extra work...you now have one more ball to juggle..the Bete's will always suck the life out of you...just when you think your in control it will stick it's tongue out at you....;-)

4

I have a Medtronic pump and a sensor built into it. I rarely use the sensor, mostly for the benefit of the doctor.

Your questions:

1) Rate of finger stick is the same on the sensor, in my experience. Finger sticks are needed to calibrate the sensor and I never felt very confident that the sensor was accurate. If I was real careful with my calibrations on day one, then the sensor seemed to be modestly reliable on day two and three.

2) Not very confident at all about making corrections on CMG numbers. Too many results are way off (yes I've seen 40s when finger stick said over 200).

3) I have had a couple CMG failures where the sensor failed to calibrate. The solution is to just change the sensor. I wasn't on the sensor very long so I don't have a lot of experience with sensor failures.

What are sensors good for? I think they are great for setting basil rates. As long as you take food and bolus out of the equation, the sensor is quite accurate. For me, the big long needle is a lot more irritation on my skin than the pump. Also, I'm on 8 to 10 sticks a day, so I don't miss many highs or lows in any case.

5

1) We check about the same as before CGM (using Dexcom 3+ yrs now. G4 since Nov 2012). Average is about 9 times/day, depending on where she is in her cycle (she's 15).

2) The Dexcom G4 is incredibly accurate most of the time, but we NEVER bolus without a fingerstick confirmation. We've seen far too many readings that are way off. We've given small amounts of carbs to head off lows, but that's the extent of my trust.

3) Depends on what kind of failure. Sensor failure can be obvious (horribly inaccurate readings, "sensor failed" errors,etc). Equipment failures may or may not be so easily determined. Dexcom has been very good about replacing sensors & equipment. We send the data file & they ship out the replacement.

We were lucky. We saw incredible accuracy with the 7+, as well as excellent range. Over time, it gained my trust to the point that a glance at the receiver overnight replaced fingersticks, unless she needed a correction. We haven't been quite that lucky with the G4, probably due in part to the almost constant hormone swings from puberty + PCOS.

6

My Questions Are These:
1) based upon real world use of CGM (and of the Dexcom G4 in particular) what is (your) actual rate of fingerstick checks while using the CGM? I test 7 to 10 times daily.

2) How much confidence do CGM users have in making corrections based upon CGM numbers? None. If I forgot my test kit or something, I might, but I always test before correcting. Often the CGM is off.

3) If and when a CGM fails, what has (or have) been the obvious failure signs?
Never had this problem. I agree with AR that sometimes the numbers get "off," but I assuume it is just me, and they always get better. Only other difficulty I have had has been the "weak signal" alert.

The CGM is a helpful tool, especially as a warning of lows and highs. But it is certainly not perfect. Mine is a Medtronic.

7

I've only had the Dexcom for about a week also, but loving it. What I'm finding is that on a good day with normal numbers, there's only a need to check at mealtimes and bedtime. (Which is certainly less than my usual 8-10x/day.) Definitely wouldn't dose insulin for meals or correction without knowing the actual BG#. On days with more highs and lows, there's more need to test. As a fellow CGM newbie, will be interested to hear what the more experienced users think.

8

Thanks to all. This is great input!

9

Hmmm...
1. I'm guessing that I've gone down to 8-9 per day from 11-12 per day, so about 25-35% fewer. Still test for most bolusing.
2. Generally I'm not making corrections based on CGM. The CGM tells me what direction I'm headed, roughly where I'm at, and then it has alarms. Generally, for me it saves strips when I'm running at a steady rate. If I'm at say 104-110 for a few hours, there's no need to test. Then other strips are saved when I'm low or high. I still have to test to bolus, but often times I can use the meter to tell what my trends are and avoid testing 4-5 times to get a clue on the curve. If my numbers are steady, I might bolus for food and not test, but generally you gotta test.
3. Usu. it won't have a reading and will show some odd pictures. Maybe the numbers will be way off. I haven't had the problem.

General thoughts on the Dexcom....

I've found it very accurate, but the key is having a reliable meter with a lot of test-retest results that are very close. Don't calibrate when you are going up or down quickly, and only calibrate a few times a day. If you first 2 numbers at start up are far apart, test a 3rd time and get the closest 2 of 3. Additionally, keeping it stuck on well is important because if is starts working lose then the sensor can get out. I use hypafix tape over mine.

For the most part it is within 15 points of meter BG. My experience is that when it is low (below 90) it is often lower than my meter. The software gives a low estimate, and the more reliable your calibration inputs are, the closer it will be to meter BG results.

10

I’ve had my G4 for about 4 months now and find it very very accurate and it actually helped me lower my a1c from 11 to 7.3 within the first 2 months of use. I find that I test less often with my dexcom, with the exception of the first day or two when starting a new sensor. Even then, I may only test often enough to calibrate if I am seeing an accurate pattern of numbers from the very beginning.
Making corrections/bolusing without a fingerstick depends on how much insulin I would be taking and how stable my Dex looks. If it’s less than a unit or two, I will sometimes bolus without checking. But if it’s a bigger amount, I will test, just to be safe.
My readings are rarely more than 10-20 points off from my meter, so I feel confident making decisions based on my Dex. I did use the Medtronic sensor a few years ago and gave up on it because it was very painful and horribly inaccurate for me, but I feel very fortunate to have had such a positive experience with dexcom.
As for failures, I am going into day 17 with my current sensor and typically get about two weeks per sensor. The typical indicators are things like the receiver skipping readings, and most often, the numbers will just be all over the place and completely inaccurate.
Good luck! I hope you guys continue to have a positive experience!

11

Also, I haven't been using the Dexcom very long, but it seems that it is more accurate the 2nd week than the first (of course the manufacturer frowns on this).

12

I would caution that comparing CGM results/use between adults & a pubertal (or nearly there) pre-teen girl can set you up for disappointment. ;) Hormonal swings lead to BG swings, which cause varying degrees of inaccuracy with a CGM The more variation in BGs, the less accurate the readings....at least that's been our experience. Those swings & their effect on readings (we've seen as much as 200 pts off from fingerstick) are why we never trust the CGM for boluses.

13

I went from 7 before the cgm up to 12+ with the cgm. I had a lot of accuracy problems with the cgm and decided it wasn’t for me… Gave up on it and now test 5-6 times a day generally

14

Ive been on the G4 for several months now, and
1)about 4 times/day compared to 8 before. i dont do a before and after meal anymore, only one or the other, and once before bed. Extra tests if i suspect the dex numbers are off
2) i have grown to really trust my cgm. i do make corrections off of it, but i find the trending to be of more value. if it starts showing a fast drop after eating w/ alot of insulin on board, i can start correcting before the low comes, or cut off a high before it gets too high.
3) sluggish readings for me, usually at the end of a sensor cycle. dex shows a flat line which isnt actually the case. changing the sensor fixes it. I usually wear the sensors for 2+ weeks and the ones that have failed did so at the 2+ week mark.
I love the dex g4..wouldnt give it up for anything!

15

the g4 definitely has a visible lag when the bgs are on a rollercoaster. the more up and down, the more off it gets, but leveling off and recalibrating seems to fix it. its more useful just to see trends when levels are fluctuating alot.

16

I have used MM CGMS for 3 years, and then Dexcom Seven+/G4 for almost 3 years.

1. With Dexcom and recent changes to obtain tighter control, I test 6-10 times/day. When I first started with MM CGMS, it was 4-6 times/day. Prior to MM CGMS, I did 4-6/day. So in both cases, no reduction due to CGMS. I increased to 6-10 BECAUSE of Dexcom accuracy, and change in my goals for tighter control. I often use the Dexcom CGMS to trigger me WHEN to BG check, for example an unexpected trend rising more than expected, after a meal, or any trend that is inconsistent with what I think it should be.

2. My confidence with MM CGMS was 0. My confidence with Dexcom varies with each day and sensor. The first couple days, I BG test for every insulin dose. If I get confidence in the sensor readings, I may do corrections or bolus, IF there was a recent BG test (2-3hrs), and the trend is consistent with what I expected, and ideally only with low or no IOB (insulin on board/active insulin). I did not start doing this until many months after starting Dexcom.

3. I have had very few failures on Dexcom, but when I did it was lost sensor/???, rather than bad readings. In 3 years, maybe had 3 sensors replaced by Dexcom.
When I do get bad reading, I do 1-3 calibrations within 15 minutes, and if it doesn't improve, I'll consider changing the sensor, especially when >7 days use.

Since your daughter has only had it 1 week, I'd suggest much more usage with 100% BG checks for every insulin dosing. After a while each person learns how accurate it is for THEM. As others mentioned, it does vary by person, #days sensor used, by location of sensor, by activity level, by how flat vs steep zig-zag trend lines, hormones/metabolism, etc, etc, etc.

It only takes ONE mis-dose, to result in a severe low, that the CGMS may fail to catch.
For example if you correct on a misleading Dexcom of 280, and BG is really 150, real BG could be down below 40, while Dexcom might be reading 160, with a correct trend, but incorrect number.

Several folks on here have posted experiences such as the above, and had unexpected lows. Their conclusion - don't do it.

17

Hi Shelby76!

I'm in the process of getting the Dexcom G4 and I was curious to know; did you feel overwhelmed at the beginning?

Also, how do find wearing it? Does it stick out a lot? I haven't had the opportunity to see it live nor on someone else :(

Thank you!

18

Hi B,

I think you will love your Dexcom. It was definitely overwhelming at first, mostly because I was nervous about the giant-looking injector needle (not bad at all), and wondering if it would be useful or just annoying (how I felt about my medtronic sensor). For me, the benefits have far outweighed any self-consciousness about how I look while wearing it :) I don't know if that is a concern of yours or not--if that is what you're asking about. I will tell you that after 20 years with diabetes, I have decided that the 'lump' on my leg, arm, stomach, or wherever from my sensor is just not worth my time or energy to worry about. I used to worry so much about people seeing my insulin pump when I started using it 12 years ago, but I have made a conscious decision to recognize that my health and quality of life trumps any worry about a physical appearance issue. My husband likes to tease me and calls me his 'bionic wife'. Hahaha!

I probably notice my dexcom more under my clothes because I wear it on my thigh 95% of the time, but I don't know how noticeable it is to other people. It sticks out a bit, but at this point, I am so used to it, that I don't really notice it anymore (as far as constantly having my eye drawn to it, or feeling it). Wearing it on my abdomen made it a bit easier to 'hide', but it was also much less accurate for me and uncomfortable, so there are potential trade-offs to whatever you decide to do.

I was at a water park this summer and I ran into a friend there. I think she was a little bit surprised to see me in a swimsuit with my dex just out there on my thigh, for all the world to see. I told her the same thing--my health and quality of life are more important than worrying about people who might stare at me. And if they want to ask me about it, all the better. It's an opportunity to educate someone else! :)

It's such an individual thing, so your best bet will be to try a few different sites and see what is most comfortable to you, both physically and psychologically. I know it can be a tough thing to get used to, but for me, it has been worth the adjustments :)

Hope this helps. Keep asking questions, there is such a wealth of information here at TuD. Good luck!