Changes to average sugar level to HbA1c calculator

hazyclaire

Active Member
Messages
25
Type of diabetes
Type 1
Treatment type
Insulin
Hi All

Just wondering, I use the average sugar level to HbA1c calculator a lot to help whilst trying to lower my HbA1c results, but the calculator results seem to recently have changed.

Previously I was aiming for below average of 9.4mmol BS and the calculator indicated that this would equal a below 7% Hba1c, whereas now 9.4mmol = 7.5% HbA1c. Does anyone know why this has changed? I found it to be quite accurate based on the old results...

Thanks
Claire
 

phoenix

Expert
Messages
5,671
Type of diabetes
Type 1
Treatment type
Pump
Looks like the one on here now gives the same results as the one on the ADA website.http://professional.diabetes.org/GlucoseCalculator.aspx
That's based on recent research using continuous glucose monitors.
Even then it's only an estimated average, there are people with higher averages and lower averages with similar HbA1cs.
You also have to take into account the fact that, even if you test many times a day you may miss spikes (say at an hour after eating) and dips so your real average may not be the same as your meter average. Glucose monitors also vary as to accuracy.
The eAg is really meant to give a guide as to your average glucose levels from a previous HbA1c rather than to predict your next one.
If you have found that the older conversions were predictive for you, then as long as you have a similar amount of tests then you could keep the same target.
 

lindisfel

Expert
Messages
5,659
Hi,
Correct me if I am wrong. HbA1c does not distinguish between the high glycators or low glycators.
Some could therefore be prediabetic and be diagnosed as diabetic?
Also some could be diabetic and be diagnosed as prediabetic?

Surely HbA1c is merely a tool that indicates integrated glucose levels for normal glycators?

By the way Phoenix, your maths is probably a lot better than mine. :) It is 50 years since I did any serious maths.
You mention spikes;
When the area under the graph is considered there may long periods of lowered glucose levels way below the putative equivalent average glucose from HbA1c, which these transient(?) or unseen spikes will not seriously affect.

NB. There has to be the same area above the Hba1c equivalent line as the 'space' below it!

Perhaps we all sleepwalk and scoff bread and potatoes. ;-)

BTW I use two different blood glucose meters and get the same results from similar GI foods.
I find my HbA1c of 50 difficult to equate to AG.
A reading of 9.0mmol/l as a EAG seems way too high! I only go over 9.0 if I deliberately abuse the bread and potatoes to see what happens to my blood glucose.
I shall have to get a private Fructosamine test (c.£140) to investigate the possibility I am a high glycator.

regards
Derek
 

phoenix

Expert
Messages
5,671
Type of diabetes
Type 1
Treatment type
Pump
lindisfel said:
Hi,
Correct me if I am wrong. HbA1c does not distinguish between the high glycators or low glycators.
Some could therefore be prediabetic and be diagnosed as diabetic?
Also some could be diabetic and be diagnosed as prediabetic?

Surely HbA1c is merely a tool that indicates integrated glucose levels for normal glycators?
Yes.
By the way Phoenix, ......

I think in my original answer I was pointing out that we will may miss times when we are higher so our real average may be higher than our meter average. (and if you are hypo aware you tend to correct quickly so don't stay low for long periods but will usually have the low recorded on your meter)

] Does equal time above/below the average count act as an exact counterbalance in terms of glycation ? That to me raises questions that I don't have the answers to!
Not every cell is glycated when it's exposed to glucose only some, yet even people with very low glucose levels have some glycated cells. I don't know what determines the number of cells that are glycated ,apart from reading various vague statements about it being to do with the amount of glucose and length of time exposed (what's the effect of 20min at 3mmol/l compared with 20min at 9mmol/l ? ). I also believe that glycation is initially reversible. (under what conditions does it become permanent?)
You need a specialist to answer these questions... and even then I suspect that no-one really knows


BTW I use two different blood glucose meters and get the same results from similar GI foods.
I find my HbA1c of 50 difficult to equate to AG.
A reading of 9.0mmol/l as a EAG seems way too high! I only go over 9.0 if I deliberately abuse the bread and potatoes to see what happens to my blood glucose.
I shall have to get a private Fructosamine test (c.£140) to investigate the possibility I am a high glycator.

The UK has refused to use the eAg at the moment for 3 reasons.
1)the group studied were not randomly selected and included people without diabetes.
2) didn't include some ethnic groups.
3) and I'll quote because it is relevant to your concerns



there is uncertainty associated with the eAG value itself, acknowledged by the authors but not evident in the formula promulgated on the ADA Web site. That uncertainty is such that two patients with the same true mean glucose level of 170 mg/dl(ie 9.3mmol/l) could have an A1C value anywhere from 6.5% (which is as low as the A1C values of the intervention groups of the VA and ACCORD [Action to Control Cardiovascular Risk in Diabetes] studies) to 9.0% (which was adversely high in the Diabetes Control and Complications Trial) (2). Clinicians are already aware of ways to reconcile this degree of uncertainty, but we—as a diabetes community—are now planning to offload this task onto our patients. As a result, based on possible conversions of A1C to eAG, patients with the same true mean glucose level of 170 mg/dl could be told that their eAG is anywhere between 140 and 212 mg/dl—with predictable consequences when they try to compare this laboratory measurement with their own meter readings.
http://care.diabetesjournals.org/content/32/1/e11.full

Of course previous formulas were just as problematic.. ( and had even less evidence for their use)
regards
Derek
 

lindisfel

Expert
Messages
5,659
Hi Phoenix,
Thank you for your very comprehensive answer, my thoughts exactly, this equivalence concept is riddled with unanswered questions.
It doesn't inspire one with confidence in the medical professions diagnosis when apparently some non diabetics can have raised Hba1c's.

I have found this site very helpful, because after losing weight on diagnosis and having no success in changing my 1c during three months and losing 10kg I now have embarked on a meter driven diet using low glycemic index foods as advised on this forum.

I think there is little doubt, if a lot of diet education was directed at the cause of low GI earlier in life a lot of diabetes and obesity would be avoided.
best wishes
Derek