HbA1c conversion to Plasma Blood Glucose Equivalent
 

Hi, I am **very** confused about HbA1c conversion to Plasma Blood Glucose averages. It seems that various sites contain various conversions and I just can't figure out which is correct.

As an example, please see: www,geocities.com/diabeteschart/bloodsugarchart.html

[note: I used a comma on purpose, otherwise the entire URL would not be printed - not sure why]

One can see that a HbA1c value of 7.0 is equal to Plasma Blood Glucose average of 172mg/dcl. Now according to the ADA a HbA1c value of 7.0 should be equal to a Plasma Blood Glucose average of 150mg/dcl. Is this chart wrong, or am I just misunderstanding something here ?

Thanks,

Adam

Hiya, Adam.

This chart has it at 170 mg/dL

http://diabetes.about.com/library/blforms/blA1ccalc.htm

And the one in my printed literature has it at 8.3 mmol/L which is 149.4 mg/dL.

So good question!

Up until about 5 years ago, home glucometers measurements related to glucose values in whole blood. An HbA1c of 7.0 corresponds to a value of about 150 mg/dL for whole blood.

Home glucometers always make their measurements on a drop of whole blood. However, the newer meters are programmed to take the whole blood measurement that they generate and convert it to a blood plasma measurement, which is 10-12% higher than the whole blood numbers. The blood plasma readings are always what the doctors' offices have used. The change in home meters programming was made so that the office and home readings would relate readily.

A HbA1c value of 7.0 converts to 172 mg/dL when it's referenced to the blood plasma scale. It is the blood plasma scale that you should now be using.

Here's a link if you wish to read more on this:

Plasma Glucose vs. Whole Blood Glucose

I nursing school, I was always taught to multiply by 18 to get the A1C to plasma blood glucose average, but another member, CarolynC posted a more accurate conversion:

To convert a HbA1c value to blood plasma glucose in mg/dl, the conversion formula is:

Plasma Blood Glucose = (HbA1c * 35.6) - 77.3

So....according to this conversion, an A1C of 7 would translate out to 171.9, so it seesm that the geocities site is the more accurate of the two.

Personally, I'm shooting for an A1C of 5 or less (100.7) which may be quite doable since my last was 5.3 (111.38).

Thanks for all of the quick responses, I really appreciate everything.

I do have one more question - just wondering if it is possible to control diabetes (over the long term) with only diet and exercise ? From what I read it is a progressive disease that just gets worse with time ...

I was diagnosed three months ago with a fasting BG of 365 and now through massive changes to my diet (following the Bernstein diet) and exercising (twice a day) my fasting BG is now around 94mg/dcl. Generally after eating my BG only rises around 10-15mg/dcl and returns back to the fasting average within 3 hours (or so). I am not sure if these numbers are good or not or how long it will be possible for me to manage without taking oral medicines (or having to go on insulin). This is just a very scary disease ...

Thanks,

Adam

confused
 

hello,
now i am really confused. i have hypoglycemia BAD and i use the accucheck complete to measure my blood sugar. Is this number 10-12% higher than the reading I would get having my blood drawn? So, when I read 70, it may really be more like 61-63? Hope not! :)

I think it will for sure if you follow the ADA diet. :p I do think that it's possible to control with diet and exercise long term as long as you keep your carb levels low and exercise consistantly.

Adam,
Those are terrific numbers!
Keep it up!
I think we can control our diabetes by controlling bg's.
Then it may look like we have reversed it, however, if we went back to eating all those carbs and not exercising we'd be back to square one with high bg's --so we can't reverse things in that sense.
I think that keeping good bg's stops the progress of diabetes, even reverses some of the complications, and allows us to live as if the condition was not there (as long as we keep a good lifestyle).
You're right it can be a scary disease, and we always need to take it seriously, but I don't think we are all bound to get worse and worse.
I hope that helps,

Uhara

Hi kay3osu! I am thinking that the lab my doctor uses is 10-12% lower than my glucometer. I measured 75 with my 'Brand-new" Freestyle meter and he got 60 from the lab.

I have been hitting 70's all weekend and have had to up my carbs about 10g per meal, also ditched my nightime dose of Metformin.

Has anyone else had a problem with lows without meds? My only perception of it occurring (other than testing) is cold hands and feet...sometimes only when it has dipped to the low 70's.

I wouldn't even worry about the lows, as I know the glucose will come back up, but I am worried about gluconeogenesis in the AM. (I can go from 81...at bed...to 103 at dawn) I know this is not bad numbers, however I am worried about the difference...and what my liver is doing to make all this happen!

(Can't wait to get an A1c!)

If you bought your glucometer within the past 4 to 5 years, it should be plasma calibrated and therefore read on the same scale as that used by your doctor. Even though your doctor draws whole blood, the measurement his lab makes is on blood plasma.

And, if you have an old meter that is whole blood calibrated, it will read low not high.