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Should diabetic thresholds (42/48 mmol/l) be age adjusted?

J

JITR

Well-Known Member
Relationship to Diabetes
Type 2
This is a spin off to avoid derailing another thread.
Robin said:
Is HbA1c is elevated in older people because of a slower turnover of red blood cells? I’m sure i’ve read something along those lines, but I’m afraid I can’t remember where. The link in @Suedon 's post upthread alludes to it, but doesn’t draw any conclusions.
In other words, is a healthy 80+ year old with an HbA1c of 40 pre-pre-diabetic at all? [Slightly edited]
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JITR said:
I think there may be a misconception here. The paper Suedon linked certainly shows HbA1c rising with age. On the one hand this could result from physiological changes due to ageing, such as a decline in the capacity of beta cells in the pancreas to produce insulin, and on the other hand factors affecting the efficacy of the HbA1c test.
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I think ageing is the obvious explanation. It would explain why some of us are diagnosed in our 70s, 80s or 90s.

The diagnostic thresholds are somewhat arbitrary numbers agreed by 'consensus' committees. They recognise HbA1c is not a precise predictor of BG levels and vice versa.

Should the thresholds of 42 (39 in USA) for pre-diabetes and 48 for diabetes type 2 be age adjusted? If so, how and why?

The link in @Suedon's post: https://pmc.ncbi.nlm.nih.gov/articles/PMC6371438/pdf/12902_2019_Article_338.pdf
 
Interesting.
I'm 72 and my last HBA1c was 46 (ie pre) down from 51
The comments on my medical records said, "safe and satisfactory for this patient"
 
I was looking at the SHIP study, linked above, and it uses the term 'increase in HbA1c with increasing age in non-diabetic individuals'. But it doesn’t seem to say why they decided they were non-diabetic, whether it was just because they were 47 or below, or whether they did other comparisons. Surely the thing to do, would be to compare sample finger prick tests, or estimates from CGMs, to see if HbA1c's in older people were consistently above what you’d expect from interpreting spot glucose readings, but nowhere could I find if this had been done.
The most I found when having a quick Google was the ubiquitous 'further research needs to be done'
 
JITR said:
Should the thresholds of 42 (39 in USA) for pre-diabetes and 48 for diabetes type 2 be age adjusted? If so, how and why?
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No I don’t think so. You’re still prediabetic or diabetic at those levels when older. But how it’s treated or now, and target hba1cs when diagnosed, should take age into account. This is the existing system so no changes needed.
 
Lucyr said:
No I don’t think so. You’re still prediabetic or diabetic at those levels when older. But how it’s treated or now, and target hba1cs when diagnosed, should take age into account. This is the existing system so no changes needed.
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Well, that leads back to my original question. Why does HbA1c rise with age. If it’s a gradual slowing down of the body's systems, then no, it doesn’t need adjusting, though treatment may vary.
But if it’s because the red blood cells behave differently, and the amount of blood glucose sticking to them is affected, that calls into question the accuracy of the HbAic. If it gives a falsely high reading, it may lead to people being diagnosed as prediabetic or diabetic when their blood glucose levels aren’t in fact raised.
The most i’ve been able to find in my pursuit of the answer is 'maybe' and 'needs more research'
 
Robin said:
Well, that leads back to my original question. Why does HbA1c rise with age. If it’s a gradual slowing down of the body's systems, then no, it doesn’t need adjusting, though treatment may vary.
But if it’s because the red blood cells behave differently, and the amount of blood glucose sticking to them is affected, that calls into question the accuracy of the HbAic. If it gives a falsely high reading, it may lead to people being diagnosed as prediabetic or diabetic when their blood glucose levels aren’t in fact raised.
The most i’ve been able to find in my pursuit of the answer is 'maybe' and 'needs more research'
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I found this among others but it seems to have a useful summery of both medications available and blood glucose 'targets' for different categories of people.
 
Yes, me too. But I eventually got to an NHS platform from a N London NHS Hospital site for Know Diabetes. Then after tedious cross checks I got to the site to be told I was not in their catchment area (they only had my email address) but I could continue to their T1 part of the site. I got there, but it didn't help from the links I then tried. I've decided this is a busted flush for me!
 
Jumping in here the above article quoted also states “ Our observation shows that conditions such as iron deficiency anemia can
‘Spuriously’ elevate A1C levels; consequently care should be taken before altering treatment regimen “
Conditions is plural and many seniors have anemia often of unknown cause. The key word to my mind is’spurious’ or false.
I was told by Dietitian that you need elevated FBS to confirm a
diagnosis and A1C isn’t sufficient.
Not sure if this is relevant but I believe it’s all related to the discussion.
 
I noted a gradual rise in HbA1c, one number each year after I approached 70 years of age. I put it down to age - but a general rather than a particular effect - my hair and nails grow more slowly, my hearing is not so acute, the optician needs to fill in all the boxes on the sheet to correct my eyesight.
After my two months using shakes and small meals last year I will be interested to see if the rise to 48 from that will drop back, and if so, by how much. I will not be overly concerned.
I lived with far higher levels before diagnosis - or rather for the 10 years when the clinic had not bothered to follow up a high test result and just kept on about 'healthy' eating.
Age brings changes, so small increases are perhaps to be accepted - though I'd be voicing concerns if the alteration was large.
 
Leadinglights said:
I found this among others but it seems to have a useful summery of both medications available and blood glucose 'targets' for different categories of people.
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This link does not work for me:

This link does:

Here below are 2 and 3 of that pdf (page 1 is the summary of anti-diabetic agents LeadingLights mentioned):

Page 2
1742685405258.png
Page 3
1742685800234.png
In terms of these guidelines my condition at diagnosis (6 weeks after my 80th birthday in 2022) was:
- Age >70;
- Latest HbA1c :104>64-75;
- Complications: hemochromatosis (excess iron, ferritin >1200)
-> Target HbA1c (>70Y): 58-64

My GPs guidance was:
- T2D is a lifelong condition. I must learn to live with it.
- Take the maximum dose of Metformin to keep my level down (no target stated, no discussion)
- A liver scan was needed to confirm hemochromatosis and assess the damage.
- Avoid red meat and leafy greens, too high in iron.

My research:
- Metformin's potential side effects were incompatible with my life style.
- Metformin does not do much good (Michael Mosley book on kitchen shelf)
- Professor Roy Taylor and his Newcastle team had shown remission is possible by diet (same book)
- If I proved to be a 'responder', my FBG could be reduced to a normal level in 7 days on a VLCD diet (Roy Taylor, 'Life without Diabetes, type 2'). Medication had to stopped (I had not stareted)

Liver scan result:
- 'You have a fatty liver' (radiologist)
- 'Treat it by diet' (radiologist)
- Downloaded the Cronometer nutrient tracking app
- Started my real food version of the Newcastle Diet the next day

Diet results:
- FBG down to 5.8 mmol/l in 7 days
- 15 kg lost after 13 weeks
- HbA1c down to 39 after 13 weeks without medication (= remission)
- 22 kg lost and HbA1c down to 32 after 26 weeks (= back to normal)
- Second liver scan result: normal (< 5% fat in liver)
 
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Alan44 said:
Interesting.
I'm 72 and my last HBA1c was 46 (ie pre) down from 51
The comments on my medical records said, "safe and satisfactory for this patient"
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I am the same age as you, my last reading was 39. I don't visit my DN as she is to put it blunt an idiot, but she told me they would be happy if my reading was 57 and that was over a year ago.
 
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Pam123 said:
I am the same age as you, my last reading was 39. I don't visit my DN as she is to put it blunt an idiot, but she told me they would be happy if my reading was 5amd that was over a year ago.
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Excuse a daft question. What does 5amd mean?
 
Here is a chart from link in @Suedon's post mentioned above

This chart shows the distribution of HbA1c in a sample of men in Pomerania. The average level rises with age in the population as a whole from 20 years old, and in the healthy subset of the cohort but not so consistently. Type 2 diabetes appears from about 40 years old.
hba1c_v_age_SHIP-TREND_03-23-2025_02.jpg
For details, please refer to 'Preventing misdiagnosis of diabetes in the elderly: age-dependent HbA1c reference
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6371438/pdf/12902_2019_Article_338.pdf
 
Leadinglights said:
Thank you, my laptop has the habit of adding all sorts of extra symbols, I didn't spot that one.
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Ah… the trailing slash… Makes a web browser think it’s looking for a folder, not a pdf document. The internet is a bit of a stickler at times :D
 
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