Just starting out with a CGM

It’s been a looooong time since I was last here, but I’m back.

About 15 years I was first diagnosed as diabetic, although they couldn’t tell me what type and put me on a 70/30 insulin mix (VILE). I got frustrated with my doctor, and found an endo to try to get some answers. After doing assorted tests, he said I’m not diabetic, and my high blood sugar was possibly due to a reaction to cortisone.

Fast forward about 10 years, and I’ve been diagnosed as diabetic again. This time I’m told I’m type 2. I’m taking metformin, and it seems to be working. The A1C is a little out, but not too bad. Forward again, and I’m taking much more metformin with an A1C of over 13. My doc puts me on more meds (Digluzide, which give me stomach cramps at first and then switched to Jalra). I’m having horrible night sweats and feel tired most of the day. I go back and tell her this, and she puts me on Levemir at night.

Covid strikes, and I’m fed up with my BS and motivated to control it to ensure I don’t get very sick if I contract corona. I contacted the endo to ask if I should be working (the government regulations state that if you have had an A1C of over 7.5 in the last 6 months you shouldn’t be teaching), as my local doctor says I can but her partner says I shouldn’t. I was hoping the endo would be the tie-breaker. He responds that he can’t advise me as he hasn’t seen me for many years.

But I notice in the reply that there is a price for ordering the Freestyle Libre sensors. I google them, and find out I don’t need a prescription for them, so I order two. While money is tight at the moment, anything that can help keep me healthy is important.

So far, I’ve worn the sensor for just about 2 days. My mind is blown by what it’s shown me so far. I have been having hypos that I wasn’t aware of. I just felt a bit tired, and have slept through them at night. I have stopped the insulin at night because clearly that would make things worse. I’ve also been surprised with how much of the time I am within range. I expected to be much higher.

Honestly, having worn it for 2 days, I can see that this CGM is going to revolutionise my life. I felt for so long that I was blundering around in the dark, but now I can actually see what’s going on and make choices based on accurate information. I’m so relieved I could cry.


Congratulations!!! Getting the CGM is the first step in YOU taking control of YOUR diabetes. There is tons of help available on this forum with others that have gone through similar experiences and are ready, willing and able to help you gain the control you seek. I was diagnosed at Joslin Boston about 30 years ago and to this date they still have not been able to “Type” my diabetes. Forget about your type and just concentrate on on achieving results that meet your goals. Ask away and we will let you know what has worked for us (we are all different) and that can save you a lot of time and expense of self experimentation. Use our experiences you like and believe will help you and disregard what does not fit your plan and expectations.

Welcome back!!!

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Congratulations and good luck!!! Now you can see the results of choices and experiments in real time. It is a brave, new world you are entering and, as @CJ114 says, there are lots of people here with lots of relevant experience and are willing to help you sort things out.

All the best of your new path.


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Are you using the newest Libre 2 ?

Generally prescription is required when getting them with insurance coverage.

Great that you’re getting great results!!

I’m using the Libre 1. My insurance isn’t going to cover it so I paid out of pocket. Ouch.

Thank you John. I do have a few noob questions!

  1. do you cover the sensor with a plaster? I am using a sticking plaster, the kind used for surgery wounds.
  2. where do you apply the sensor? At the moment I’ve got mine about three quarters of the way around my arm. Should it be on the back?
  3. is it normal to be tender and sore for the first day? Today has been better, but yesterday it was sore if I moved a certain way.
  4. how many times can you read the sensor? Does it have a battery that will run out? I’ve been a bit obsessive so far, checking very often.
  5. the log on my app only shows when I have read the sensor. Is it capturing the other data too? I thought it took a reading every minute?

Thanks for the welcome CJ! This thing is such a game changer for me so far.

CGM’s are revolutionary and they are only getting better. They are not perfect, but damn they are good.

This is from Abbott site, regarding Libre 14 day.
How frequently does the sensor capture and store glucose readings?

The FreeStyle Libre 14 day sensor automatically captures the glucose concentration in the interstitial fluid every minute. It also automatically records the glucose concentration every 15 minutes, storing that data in a rolling 8 hour log.

So it records (I think it mean saves a reading to send at next scan) each 15 minutes. But does not send all individual reading at scan. Guessing it sends either last or average from that 15 minute period.


Let me qualify my comments: I actually us a Dexcom G6, rather than a Freestyle Libre. They have a lot of common characteristics, but differ in many ways too. I’ll do my best to answer based on my understanding of how a Libre works … and will assume that if I misspeak, a “real” Libre user will correct me.

So, here we go in order:

  1. How much problem you have with sensor adhesion is a big variable. I can wear a Dexcom for 10 days with no problem … although I DID start with on overwrap of the type you describe for my first few sensors to be certain. Some people always use over tape, others only when the outer edge of the sensor tape begins to pull away from their skin. Others also use SkinTac … an adhesive between their skin and the sensor. And some folks are allergic to the adhesive on the sensor … which complicates everything.

  2. I also wear my sensor on the back of my arm, about midway between shoulder and elbow, but rotated about 30 degrees inward towards my body…
    Some people use abdomen, upper thigh, or buttocks. Most people get the best results in a fleshy, rather than overly muscled, area and one where they are less likely to “scrape off” the sensor.

  3. With my Dexcom, I virtually NEVER feel anything aside from an occasional slight sting from the inserter. The one time I did feel the sensor during some movements was when I tried to use my thigh. I believe that if the sensor is in or close to muscle, you are more likely to feel an occasional “twinge” and are also less likely to get accurate readings.

  4. I believe that the Freestyle takes a reading once a minute. So scanning more frequently than that won’t help. It also maintains an 8-hour “rolling” log of measurements taken every 15 minutes. I expect that there is a way to access that log, but I don’t know exactly how to do that. Maybe a “real” Freestyle user can help with that. Yes, the sensor has a battery that runs the electronics, makes the measurements, etc. My guess is that you can read about as often as you like without running down the battery over 14 days. Libre users should have more to add here.

  5. I expect that there must be a way to also see the 15-minute interval log … but a Libre user should be able to help. It doesn’t actually store the reading it takes every minute, but if you can see 15-minute intervals you will have as lot of information to digest.

Best of luck … I’m confident you are going to learn a lot in the coming weeks.


I’m so familiar with that. When I finally sought an endo after self-managing for many years (because I finally had insurance to pay for better meds), I too had an A1c of 13. Everyone screamed “take more insulin!”, despite me insisting I struggle with lows. I was just labeled “combative” for not wanting more insulin.

CGM really is an eye opener! I was able to figure out the lows and avoid the rebound highs later.

Hope you come around and participate more. I never stop learning here.

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Another noob question. My Libre showed a hypo of 3.7 (66.6 mg/dl), but when I tested with my meter it was 6 (108 mg/dl). This is a huge difference! Why?!?! I understand there’s a lag between the interstitial and blood glucose readings. And then there’s also the possibility that either the sensor or my meter is off. I’m using the Accuchek Active meter system at the moment. But it’s such a HUGE difference!!!

Is it normal for it to be this big?

I haven’t been using my Libre (1) for all that long yet. I started June 10th, but I have been pretty geeky about it. I have been comparing readings between the sensor and my One Touch meter - I even bought some strips for the meter that is part of the reader that comes with the Libre and compared the Libre sensor, Libre meter and the One Touch meter for a week or so. What I have found is that there is more discrepancy the higher or lower I am. Also, if you see the arrow on your app pointing up or down, it indicates that your BGL is trending up or down. Since the meter reads what’s in you blood right now and the sensor reads interstacial fluid (not blood) it sometimes takes a bit for the sensor to catch up to the meter. If I need to make a dosing decision, I trust the meter more than the sensor.

If you are using the app on a smart phone, give it a few days and your charts will start to fill in. Those charts offer some really good insight! Any advice I may give is worth exactly what you paid for it :wink:


I used a libre for a while before my Dexcom now and I still use a Libre on my diabetic dog.

It will always be off your meter reading.

  1. You want to make sure you do a meter test and wait 10-20 minutes to compare it against your Libre reading. the Libre reads interstitial fluid so it will always be behind from the meter. Always only compare against a sideways arrow reading.
  2. My Libre’s and the same with my dog usually vary most of the time by about the same amount. So it is usually 15 points give or take a little off each time so to speak. I learned to dose by allowing for that without still having to finger prick all day. That was me though and can vary per person. If you are avid about exacts, you will need to do a meter test for that.
  3. They can be off more at higher numbers, so it’s best to compare it with the numbers you will be at the most. Like around 100, 110 or 120?
  4. I had good success with the Libre staying on without extra help, my Dexcom is a completely different story. If you hit the Libre just right though it can pop off easily, like hitting it on a doorway or the car seat belt etc. Extra adhesive like skin tac would be beneficial if that’s an issue. We use Skin Tac on my dogs just around the edges, but it sure seems like the adhesive has gotten better on it as we had to cut down on how much skin tac we were using as we actually were having a hard time getting it off of her even with tac away.
  5. I used to apply them on the back of my arms, alternating each arm and slowly moving from higher to lower, that worked really well. You can put it towards the sides but you are more likely to bump it and pop it off, it just depends on your habits I guess. Libre can send you their recommendations of extra adhesions to use.
  6. I was only tender one time. You are more likely to be tender if you hit a muscle etc. The back of the arm usually has enough fat that isn’t as likely to happen.
  7. It does capture readings every minute, it has a memory for I believe 8 hours, so you don’t need to keep scanning it unless you want to see actual numbers in your log. Those numbers sometimes are useful to look at, but you usually don’t need numerous unless you are trying to stop a low. The graph will always be filled in for up to 8 hours. Sometimes there will be a random number when you scan that reads higher or lower than what your graph will show. It likes to level out the graph if it is a random high number.
    8)Keep in mind if one pops off, they usually will replace a couple a year for that, maybe more. If it is off by too much, too inaccurate, they will replace it too. I think their requirement is 30% off. So you need to have a couple of readings 30% off when you call. Years ago they required it be a freestyle strip in the meter reading to compare it against. I purposely bought a small amount of strips so I had that to use when I called them. Who you talk to can really vary, I used to hang up when a certain rep answered because they were horrible to get a replacement out of. Whereas others can be really easy sometimes.
  8. The phone ap on the iphone provides easier to see graphs and more information. I did fine with just the reader on me but downloaded the ap for my dog and once I did we just about only use that to look at now. It’s much nicer. More logs on each page, easier to just do one swipe for the previous day etc.

The Libre was such an eye opener for me too when I started using it!