hba1c says prediabetes, blood glucose appears normal

[lovespinach]

How many of you have been 'diagnosed with pre-diabetes ' solely on the basis of hba1c?
Has anyone else found a big discrepancy between hba1c and blood sugar results?
Ok so my hba1c was 43 last April, doc said do low carbs, but still hba1c was 44 in July and still 44 in November, despite very low carb diet and unwillingly losing 8kg ( - from a BMI of 19 I dropped to 17) .
So then a diabetic friend said 'Have you actually tested your blood glucose? Didn't the doc even test it? - I said no - I had just trusted the doc that my blood sugars were higher than ideal and I was 'heading for type 2 diabetes' ( her words ).So just before Christmas I got a meter and began testing. I know that hba1c and blood sugar results do not strictly convert and the calculated correlation can have a 15% error either way, but what I've discovered ( not just with my meter, I borrowed a friend's too so it's not just mine is measuring wrong) is that the highest spike I've been able to record is 8.8mmol/L (and that's 45 mins after deliberately eating over 50g neat marzipan and two spoonfuls of marmalade, while icing the christmas cake !!) but 2 hrs 30 mins after the marzipan binge my sugars were at 4.1. I have repeated this several times ie trying to catch a sugar spike but every time the peak is between 6.5 and 8.5 ,and 2 -3 hours after the 'binge ' I'm back to 4 point something or low 5point something at the tops.If I eat low carb meals the 2 hours post meal average is about 5.5. With 55 readings over the last month I average 5.2mmol/L. This 'converts' to hba1c of 29.8mmol/mol using the diabetes uk converter below
https://www.diabetes.co.uk/hba1c-to-blood-sugar-level-converter.html
Does anyone else have a massive discrepancy like this? My blood sugars appear to be entirely normal and indicate an hba1c FIFTY % below the measured one, I've looked up some research and some people are talking about a heritable 'glycation gap' where these 2 do not match up.
Ideas , anyone?

 

[Drummer]

My blood glucose is usually fairly low after eating - I saw 5.6 after two Christmas dinners - yet my Hba1c is seemingly stuck on 42. I think this is because I went so long without diagnosis - I was sensitive to carbs all my adult life, eating low carb helped a lot, but I was 65years old when finally tested.

 

[Robin]

Do you have a tendency to anaemia? This can make the HbA1c appear higher, as it measures how much glucose has bound to the red blood cells over the previous 3 months. So if you’ve got fewer than normal red blood cells, more glucose will have to bind to each of the existing cells, and the result will seem higher.

 

[Eddy Edson]

Besides anemia, there's just simple person-to-person variance in the avg age of red blood cells. They live for about 90 days on average, die off & get replaced by new ones. But that 90 days is just an average and there is significant individual variance.

The standard HbA1c <-> blood glucose association generally works for the average 90 day RBC life, but it becomes less accurate as RBC life varies from that average.

If your red blood cells are shorter-lived than the average, they have less time to get "sugared" and your HbA1c will read "low" compared to your actual BG; and vice versa.

The Massachusetts General group which put together the original study establishing the standard HbA1c <-> BG association says that for one-in-three people, the actual BG level will differ by more than 0.8 mmol/L from the level estimated from HbA1c - mainly due to this difference in RBC life-spans.

An HbA1c of 44 would predict an avg BG level of about 7.3 mmol/L, on the standard association. But for one-in-three people, the actual BG could be less than 6.5 or greater than 8.1. It's not a precise thing and a good doctor will recognise this.

If you want to delve into it more, you could self-fund a couple of Libre sensors and see what results they deliver for yr avg BG (recognising that the Libre can also be squidgy and you need some fingerpricks to check its accuracy).

For science stuff: https://www.ncbi.nlm.nih.gov/pubmed/27708063

 

[lovespinach]

Thanks for your ideas-

• I've never ever been told I'm anaemic.
• re accuracy of hba1c- because the hba1c tests I've had are spread over 16 April to November 27th that's 210 days so surely any red blood cell circulating at the start will be long since replaced at the end, don't you think?
• I completely understand about hba1c of 44 could be a BG as low as 6.5 but mine is 5.2mmol/L over 55 readings at all times, LOTS of post-prandial, and including my attempts to push up my BG by having sugar binge... thanks for your idea about Libre sensor but they're pretty expensive , tho I could see if the endocrinologist I've been sent to will get me one on prescription.....

My main reason for pursuing this is I want to find out whether I actually do have prediabetes or don't I - my GP was actually quite alarmist last April,so I cut out almost all carbs, absolutely all added sugar, felt rubbish, snapped at my family, lost over 15% of my body weight , ended up underweight skin and bone.......for what? Was it all a 'mistake' because they never bothered to check my actual blood sugars?

So do I need to keep to a low carb diet or not? I love veg anyway...but I've only managed to stop losing weight by putting some bread and cereal back in.

 

[everydayupsanddowns]

Hello and welcome to the forum @lovespinach

Congratulations on your good BG results. Just to add another factor into your consideration, I’ve also heard of ‘high glycators’ and ‘low glycators’ where two different people with identical BG profiles might have significantly different HbA1c results, depending on the propensity of different people’s blood to be affected by glucose.

It would certainly be worth having a conversation with your GP and getting their thoughts, particularly since you have intentionally examined the effect of a very high and fast-acting carbohydrate load.

 

[Ralph-YK]

I completely understand about hba1c of 44 could be a BG as low as 6.5 but mine is 5.2mmol/L over 55 readings at all times,

In the measures used for the HbA1c test, 48 (new scale) is 6.5 (old numbers).
The old scale for the HbA1c does not directly match a finger prick test figure. That's a different measurement in another scale.

 

[Eddy Edson]

Thanks for your ideas-

• I've never ever been told I'm anaemic.
• re accuracy of hba1c- because the hba1c tests I've had are spread over 16 April to November 27th that's 210 days so surely any red blood cell circulating at the start will be long since replaced at the end, don't you think?
• I completely understand about hba1c of 44 could be a BG as low as 6.5 but mine is 5.2mmol/L over 55 readings at all times, LOTS of post-prandial, and including my attempts to push up my BG by having sugar binge... thanks for your idea about Libre sensor but they're pretty expensive , tho I could see if the endocrinologist I've been sent to will get me one on prescription.....

My main reason for pursuing this is I want to find out whether I actually do have prediabetes or don't I - my GP was actually quite alarmist last April,so I cut out almost all carbs, absolutely all added sugar, felt rubbish, snapped at my family, lost over 15% of my body weight , ended up underweight skin and bone.......for what? Was it all a 'mistake' because they never bothered to check my actual blood sugars?

So do I need to keep to a low carb diet or not? I love veg anyway...but I've only managed to stop losing weight by putting some bread and cereal back in.

Anyway, good you're seeing an endo.

On a side note, I think it's inappropriate for a doc to be "alarmist" about "pre-diabetes", which is in many ways a pretty dubious categorisation. There is just about sod-all evidence of complication risks at pre-diabetic levels, and actually only a small number of pre-diabetics progress to full-blown diabetes. This is worth a read: https://science.sciencemag.org/content/363/6431/1026

 

[lovespinach]

Thanks for that - I've begun to realise that the GP really didn't have enough to go on to say what she did.
Interesting article about drug company motivation....

 

[trophywench]

The thing to also remember is , a finger prick blood test on a meter is ONLY your BG in the instant you pricked your finger. It does not refelect what the BG is doing for every other second of the day and night. Hence it cannot be relied on to show what the BG is doing 'generally' and that's why they use the HbA1c which shows how much unused glucose has adhered to the red blood cells over the last 90-ish days.

Neither is going to cover all possibilities with all individuals - end of story!

But it absolutely remains that the HBA1c is a more reliable test than any number of finger pricks.

 

[trishp]

Hi Eddy Edson,

Would you share what you mean by "moderate carbs" when describing your way of eating? I'm finding that there does not seem to be an agreed-upon number for low, moderate, and high carbs. How many grams a day do you consume? Thanks!

 

[everydayupsanddowns]

Hi Eddy Edson,

Would you share what you mean by "moderate carbs" when describing your way of eating? I'm finding that there does not seem to be an agreed-upon number for low, moderate, and high carbs. How many grams a day do you consume? Thanks!

I’m sure Eddy will give his own suggestions, and you are right there are no agreed standards.

This is my basic sketch version, based on people I’ve seen on the forum over the years.

National guidelines 250-300g / day

Moderate 150-200g / day

Low-ish 100-120g / day

Low 80-100g / day

Very low / Ketosis 40-50g and lower.

 

[Eddy Edson]

I’m sure Eddy will give his own suggestions, and you are right there are no agreed standards.

This is my basic sketch version, based on people I’ve seen on the forum over the years.

National guidelines 250-300g / day

Moderate 150-200g / day

Low-ish 100-120g / day

Low 80-100g / day

Very low / Ketosis 40-50g and lower.

Typo for "moderate", I think? - suppose you mean 130g-200g.

 

[Eddy Edson]

Hi Eddy Edson,

Would you share what you mean by "moderate carbs" when describing your way of eating? I'm finding that there does not seem to be an agreed-upon number for low, moderate, and high carbs. How many grams a day do you consume? Thanks!

Hi & welcome! For me it ends up being around 120g - 175g, usually. But actually I use "moderate" more in the sense of an attitude than referring to specific targets.

When I was getting things under control at the beginning of my D-voyage I didn't count carbs, really; more a matter of testing before & after eating and changing what I ate and/or portion sizes to keep BG levels from going too high.

I absolutely did not want to cut carbs from healthy things like fruit, melon, whole grains any more than I had to. Everything I researched made it clear that cardiovascular issues were at least as important as BG, maybe more so, and replacing those kind of carbs with saturated fats etc makes zero sense.

(By "research" I mean eg consensus recommendations and studies from major expert groups, not eg unqualified people posting on message boards. Taking nutritional advice from message boards is another thing which makes zero sense.)

As a result of this I worked out that I was really sensitive to grains - I probably have been forever; that seems like a common enough thing. Finding a replacement source for fibre, very important for CV health according to the same expert sources, led to eating lots of seeds.

So: never really a carb target in terms of g-per-day, more that I landed on what is often called "moderate carb" as a result of self-testing. The landing point, in terms of how many carbs and what kinds of carbs, will be different for everybody - there aren't any "rules", unfortunately.

 

[everydayupsanddowns]

Typo for "moderate", I think? - suppose you mean 130g-200g.

Hehe! No... I was aware it was a bit untidy and ’gappy’

 

[Ralph-YK]

Hi Eddy Edson,

Would you share what you mean by "moderate carbs" when describing your way of eating? I'm finding that there does not seem to be an agreed-upon number for low, moderate, and high carbs. How many grams a day do you consume? Thanks!

That's the problems with the term "low carb". HCP would say anything from 130g down is low carb. So it could apply to someone doing 130g a day, or 30g a day.

 

[trishp]

Thanks for the comments. I've been researching for a project (can we share websites on here?) and interviewing nutritionists, etc. It's interesting that the numbers vary so widely. As someone mentioned, there does not appear to be a definitive gram count for low/moderate/high daily carb intake. Certainly, the folks online who are trying to follow a 'low carb' diet are plucking numbers almost at random. Anyway, whenever I see someone attach an adjective to the word carb, I always have to ask what their number is. Thanks, Eddy!

 

[trophywench]

Moderation in all things - except laughter! to quote Alan Shanley.