Blood Glucose Variability Study

Looks like a study that actually (almost) makes sense was published:

Mean HbA1c, HbA1c variability, and mortality in people with diabetes aged 70 years and older: a retrospective cohort study


Have they found similar results in younger populations? Or, can they attribute this to age?

This paragraph sums it up well.

Both low and high levels of glycaemic control were associated with an increased mortality risk, and the level of variability also seems to be an important factor, suggesting that a stable glycaemic level in the middle range is associated with lower risk. Glycaemic variability, as assessed by variability over time in HbA1c, might be an important factor in understanding mortality risk in older people with diabetes.

I have a lot of respect for the negative effects of high BG variability. Anyone who has lived with insulin for any length of time, knows that the body does not like large swings in blood glucose. Sustained BG variability, like riding the gluco-coaster, saps energy and erodes well-being.

I suspect geriatric-patient clinicians will try to implement this study’s finding and focus on low and high A1c’s and fail to address variability measures. Without CGM data, variability is hard to measure. This study looks at BG variability as “variability over time in HbA1c.” I suspect that this is not a good measure of BG variability.

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I agree @Terry4 – hence my “(almost)” comment. I’m glad to see someone paying attention to BG variability, albeit using the wrong measure. I’m guessing that there wasn’t enough aggregated data to do the analysis based on daily BG variability, so they copped onto a bigger data source in HbA1c.

Except that “A1C Variability” is not what we here usually talk about, when we talk about bg variability.

The A1C Variability in the study was measured with a delta-time of months, and we more commonly talk about bg variability hour-to-hour (or even more fine grained).

All that said, even for us younger folks, a wide swing in A1C between consecutive doctor visits (6 months or so apart) is a warning sign that something is going on.


Now it is. But in the NPH, R days it was quite common, from personal experience.

I think moving to carb counting and basal bolus routines helped flatten the A1C variability, and in many/most cases A1C itself.

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I quote under the findings section:

“The data showed a J-shaped distribution for mortality risk in both sexes, with significant increases with HbA1c values greater than 8% (64 mmol/mol) and less than 6% (42 mmol/mol),”

It seems according to this, the safe zone is 6% - 8%
Does this mean targetting 5% for 70 years and older diabetics is teasing death?

I really think that depends on how stable BGs that 5% represents – if it’s 5% with an SD of 35, I’d say it’s probably dangerous. But an SD of 10 would be quite safe…
The key will be to see what the limits really are — as well as the consequences for other options.

Broadly there are big issues with the low A1C bins in studies of risks of death and complications. There are simply very few “real diabetics” with A1C’s in the sub-6% range. Remember, when you look at the very vocal folks posting to tudiabetes saying their A1C is 4.3% or 5.2% or whatever, you are looking at a tiny fraction of a tiny percent of all diabetics who are able to get that kind of control.

I think their statistics in the sub-6% A1C bin were not sufficient to say anything definitive. There is ALMOST NO DATA in the below 6% bin. Different models they used show a rise or not a rise or a continued decrease in mortality as A1C goes towards 6%. The supposed rise in mortality below 6% is very minor if it is there at all.

One of the curves/models (blue line) shows an eensy teensy rise as 6% is approached from above. A different curve/model (red line) may (females) or may not (males) show a rise as 6% is approached. And the third curve/model (green line) shows a continuned decline in mortality continuing as A1C falls towards 6%.

Especially look at the error bars on the points. You might think if you look only at the bottom red curve, that an A1C of 9.2 is safer than an A1C of 8.7. But obviously the error bars on the points make it clear this is just a large statistical fluctuation.

The lack of data in the super-low A1C bins goes all the way back to the original DCCT publications in the 1990’s. And even the original DCCT mused about a possible risk in overall mortality in those low A1C bins but it’s hard to draw any conclusions because the statistics in that bin are so low.


Dr. Richard Bernstein turned 80 last year and maintains an A1c of 4.5 – and advocates this as a general goal.

Realistically, how many diabetics can attain that goal considering the daily struggles of ordinary diabetics’ life? Perhaps 1% of 1%? I realize the constant attention required to attain 4.5% average, with the glucagon kit always ready for use. I do know that a very very few have attained this. BUT LET US NOT DIE TRYING TO GET IT.

Yea, I guess it could be interpreted that way. But, as always, it depends on the individual circumstances, right?

What I have always wanted to know (but, may be impossible) is if we see decreased variability over time, associated with age, since young, healthy, active (and perhaps, female) bodies tend to pump a lot of hormone and tend to have more variability in lifestyle. Seems endocrinologically significant to me. I guess I would like to know the effect of age on variability to get a better idea of a baseline. Does that make sense? I may not have explained it well. BG low.

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Giving diabetics a realistic/attainable goal with less risk of hypos is a safer advise, say 6% - 8% with emphasis to less variability. Most diabetics will probably say “that’s doable”.

Yeah, that’s what I think gets recommended, even for young diabetics that are higher risk due to multiple chronic conditions or variable lifestyle. That’s standard, I think. Older populations are naturally higher risk, but it depends on the person.

I think some research really needs to be done with this group. Up until now everything about Dr. Bernstein and those following his recommendations is anecdotal. According to this site, only 2.86% of Type 1s have an A1c of less than 6.0%.

I’ve been eating (mostly) very low carb for the past year and, although it does help substantially with BG stability, I still have BG fluctuations every day and have yet to break through that 6.0% A1c barrier into the 5% range. I would be interested to know the risks and benefits that come with aiming lower, especially as someone several decades into diabetes with many decades to go in this journey. I enjoy eating low-carb when I’m on vacation and don’t have much on my plate. But when I’m working full-time and going to school and other activities most weeknights, it has a high cost in terms of the effort it takes to continue (especially because I can’t eat a majority of low-carb processed foods due to multiple food allergies).


Unattainable - or difficult to attain - goals aren’t necessarily bad. And no, aiming for 4.5% average with big swings in BG, necessitating a glucagon kit in your back pocket at all times, is not a good idea. BUT, taking steps to minimize the BG swings (for example, Dr. Bernstein’s approach limits carbs to 30g/day and requires a fairly regimented life) can get there - or close - with a lot less risk.

For a period of 18 months or so, I maintained an A1c of 4.9% with no severe lows, though some mild ones. I changed things to eliminate those mild lows, and my A1c rose to around 5.4-5.6%. (I have a glucagon kit in the house, but I’ve never been even close to considering using it.) I think I can push that down a bit and yes, it will take some changes and some work. Just because a goal seems unattainable doesn’t mean it is - and certainly doesn’t mean it’s not worthwhile! (After all, finding a CURE for T1D seems unattainable, too – but is definitely worth pursuing, isn’t it!?)

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You’re so close. Just a little more effort, you will be there. 5% club.
I’m in awe with these very few control successful people. @Thas in mind.
Cream of the diabetic crop!

I’m currently off the low-carb wagon for the past two weeks or so, mostly due to business. That is by far the hardest time for me. Out of the house for 12 hours a day, no car so having to carry 100% of my own food on my back (which I have to find time to make at some point prior). So it really comes down to a question of whether even more effort is worth it in terms of long-term payoff. That’s hard to know when there really have not been any studies of Type 1s with normal A1c and blood sugar levels.

Eating very low-carb definitely helps with BG stability, and that is mostly what keeps me going with it. I just can’t stand the rollercoaster of high carbs for long. I need to actively “sugar surf” day and night in addition to low-carb to achieve stability; low-carb alone doesn’t cut it. And my “stability” is usually a standard deviation higher than what many in the 5% club hit.

Don’t beat yourself up trying to get onto the 5% wagon. You are doing great where you are. Good job.

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A general goal that less than 0.03% of all T1’s are currently meeting.

I’m all for encouraging good bg control, don’t get me wrong! With an A1C consistently less than 6% I’m in in the top few percent myself already. But how much effort should we spend bringing my A1C down from 5.5% to 4.5%, when the actual expected improvement from bringing someone else down from 12% to 11% A1C is much larger? And so many more (6% of all T1’s) are already above 11% A1C.

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