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Libre 2 Plus Estimated A1C

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peterb999

Well-Known Member
Messages
86
Type of diabetes
Type 2
Treatment type
Tablets (oral)
Hi All,

I'm currently on holiday in Turkey this week (and missing the dreadful weather at home in the uk fortunately).

Quick background, I was diagnosed in Jan 2021 when I was 20 stone. It took a while to get used to it, but within three months I was 70 and then down to 58 then 48 and then 38 in the last blood test in August 2025.

I have lost a lot of weight and I'm now 13.5 stone and I am very strict with myself trying to keep the carbs as low as possible. I think I eat less than 100g a day in carbs. I really don't eat much at all compared to what I used to. I have breakfast of eggs and bacon usually, sometimes I skip lunch and then have dinner of say 2 pork chops with salad. I don't ever eat anything to do with potatoes.

I have had a test Libre 2 about a month after my last blood test which I found very very useful. After the 14 days it said my estimated A1C was 33.

As I am on an all-inclusive Turkey holiday (I thought this was a good idea as it is all buffet type food so I can just have things like fish, cheese, salad, chicked, beef etc.) I have been eating quite a lot more than I would normally have.
I decided to buy a libre 2 to use while here as I wanted to make sure I wasn't getting high figures when eating food I wouldn't normally eat.

It's been fine all the time I've been here so far and the most it had gone up to in the last couple of days was 7.1 but very quickly (within 40 minutes shot back down to around 4.9 - 5.2. I started to get a bit more adventurous and had two slices of cheesecake (1 chocolate) which I really enjoyed. My BG went to 8.6 but then, again, came down within about 40 minutes to 5.2 - 5.6. Today I had another two slices of cheesecake with lunch and another two slices with dinner (and had two scoops of chocolate ice cream at 3.30pm).

Again my BG went up, this time to 8.9 but then came back down very quickly again and stayed in the low 5s. I have been drinking about 10 0.3L beers each day as well each day and that doesn't seem to raise my BG much at all.

The device has now estimated my A1C to be a staggering 29mmol (4.8%). Do you think that this reader could be faulty? surely I can't be anywhere near 29. I am a bit confused - i would be really pleased but I am completely suspicious of it. Unfortunately I don't ever prick my finger as I haven't got that type of testing kit and I've always been a little bit scared of pricking myself - I find the stick on Libre to be great and not at all painful.

Has anyone else ever had a faulty one, or one that reads far too low? It can't be completely faulty as it does go up after eating.
 
Hi - really well done. My very limited experience with the libre led me to conclude that it was great for trends and and finding out what was going on when you couldn't do a blood test via glucometer, but that it was a bit over-optimistic (on the low side, that is) with readings and more so with predictions.

In one sense it doesn't really matter, because your BG will be what it will be at the HbA1c test, but it could leave you slightly disappointed that your good result, while still good, is not as good as predicted. Bit like being told you'd won £100, and then that, actually, the win is 'only' £50.

I've had similar experiences to you in being able to cope with food that raises BG but the system deals with it, or at least seems to deal with it. This mainly concerns Italian gelato and tiramisu. I theorise on no actual proof whatsoever that I have regained the first phase insulin response, so that takes care of the glucose and ensures the rise is both limited and short - I'd expect 8ish around 40 minutes after a gelato, but back to standard 4.7-5.4 after an hour or so. Obviously I lost this in the past through my food being too carby for me, and the trick needs to be avoiding the same mistake again.
 
Hi @peterb999 , I found the Libre CGM s estimate lower than actual, for Ac1s . I’ve used in the past Libre 1 , 2 and 2 plus , they all read lower than actual. Not a big difference, but enough to make you feel a bit deflated. I’m on the Libre 3 , it’s estimating my Ac1 % at 5.9 . I’m interested to know if the 3 is more accurate than its predecessors.

The Libre gives you an estimate Ac1 number based on its continuous readings. So it’s not actually measuring the average blood sugar level in your blood over the past 2 - 3 months. In short the CGM is giving you its best prediction based on the data it has accumulated which may well differ from the actual 3 month blood sugar average tested from blood. I find the Time in Range feature a very good feature.

The value of these devices for Type 2 diabetes, as @KennyA points out, is its ability to continuously monitor your blood 24/7 , so it gives you a better idea of trends and patterns. The Ac1 is a nice addition, but the only way to know what your Ac1 result will be is to have the Ac1 test.
 
Thanks for the responses, it is appreciated. It makes sense that it seems to be showing the figures lower - but as you say it is showing me that my BG does come back down a lot quicker than it was when I first used the test one.

I thought 29 was a bit strange - however, with the test libre a couple of months ago it would show 33 (when I was about 38) so I guess that 29 means I am lower than I was but just not as low as that. I've enjoyed the chocolate things the last couple of days but to be honest not as much as I thought I would so I won't be having them again. Next week I'll be back on the "wagon" though I actually really enjoy what I eat at home now. My life has got so much better in some ways since getting divorced last year - it's very sad in some respects and I miss my ex-wife a lot but there is no getting away from it that I am happier now. I have found it much easier to lose weight and to restrict eating when happier - I guess I now understand when people talk about comfort eating.
 
Late to the party but I agree with what’s been said. I have seemed to regain the first phase insulin response as Kenny describes, I can now ‘get away with’ the odd carby transgressions, in that I get an initial rise in blood sugar, rarely above 8 but it drops back rapidly.
With regard to your Libre HbA1c prediction, I used Libres for a few years (recently changed to Dexcom) and the Libre result was always below my lab results, by as much as 8 on one occasion.
 
I have tried on a couple of occasions to diet strictly to get my Hba1c down. For the last effort the Libre was used for exactly the 3 months for which I dieted. The Libre predicted an Hba1c of 35 early into the test and didn't vary by much from then on. The official Hba1c was 48 which although a disappointment has impressed DN. The Libre always predicts a lower figure.
 
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