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How reliable are HbA1c tests?

Do people really get "told" what to eat? My mother insisted I should eat greens but since then nobody has told me to eat anything. Of course there has been the media saying "go to work on an egg", then "don't eat eggs they have salmonella" then "you can eat as many eggs as you like" all that just washed over me. As for the medical profession, they have never mentioned food, I didn't see the Eatwell Plate until I went on a DESMOND course. Surely the only people "given advice" about what to eat are already seriously over weight.
ETA: Sorry this is off topic.
 
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I must just have been unlucky with my GPs but yes, I have been pushed to eat according to the normal rules. I was threatened with being taken to hospital and 'fed properly' during my second pregnancy.
 
Thanks to @Bill_St I found what I was looking for. McCormack and Holmes from UBC, Vancouver, have put a tool on the web, which lets you compare subsequent measurements.
Your results may vary: the imprecision of medical measurements
https://www.bmj.com/content/368/bmj.m149

This confirms what I already knew for blood glucose tests as I have a sufficient sample to estimate their variation myself,
but I now could do the same for my Hb1Ac and it tells me that 42 and 55 mmol/mol are not compatible. This is what I expected and we've discussed possible reasons for this above. For scientists, they give a 95% confidence interval of 42+-8 mmol/mol for the first test.
 
The plot thickens.

First the good news: I managed to lose that couple of pounds I wanted to and keep it off; I am back at the same weight as before Christmas. The good weather helps as I do lots of cycling. I am also having online physiotherapy sessions for my shoulder, so fingers crossed on this front as well.

With my weight my blood sugar levels - before breakfast - came down to about 6.0 mmol/l again. This was at the beginning of May, so I was rather pleased. Then something happened for which I don't have an explanation. About a month ago my pre-breakfast levels jumped up to about 7.0 mmol/l on average. First I thought it was a blip, but by now it has stayed around that level for five weeks. The graph of the data literally looks like a step function of +1.0 at the beginning of May. I honestly do not recall changing anything at this time. Due to Covid my routine has been more stable than ever. Hence I am at a bit of a loss of what is going on. Any ideas anyone?

I also started to measure BS levels 2 hours after breakfast or 3 hours when I am stuck in meetings. While I need to do more measurements, it looks like my post brandial levels increase by 1 to 3 mmol/l. I hear that up to 2 is ok, but how bad is 3?
 
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Did you open a new pot of strips at that time?

a post prandial of +3 is more than I want and would change the meal if I got that, probably not the end of the world and as a one off a learning exercise but as a regular thing it’s adding to the drip feed of potential damage.
 
I like @HSSS would not like a rise of 3. Maybe for a particular occasion or celebration but for a normal meal- no. Even if you start in the 4s which is low you end up in the 7s which is high. Some say damage can occur at 7.8 so I try to keep out of the 7s completely. I don't always succeed but if I am it is usually either stress, sickness or an artificial sweetener. I then get rid of that type of artificial sweetener if that is the cause.

I think that it is best to avoid spikes at all if possible but as said above all we can do is our best. Perfection is not always possible. I know that this is for life so I'm will slip up now and again- that is why I keep regular testing- I don't want to carb creep and end up with some real health problems.
 

If you were stuck at home it could be a change in activity levels? If diet hasn't changed. I'd be looking at those meals where you were hitting PPL rises of 3 mmol and the carb content, possibly combined with protein level being protein can cause rises later in some people.
 
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