Why I don't think HbA1c is great for low carb people

(Bob M) #1

I never got my HbA1c tested until I was low carb/keto for a while. About 6 months into low carb, it was 5.4. It went to 5.6 then down all the way to 4.9, and now is 5.1 the last few times. On 1/1/20, I will be low carb/keto 6 years.

The problem I see with HbA1c, for those who have been keto for a while, is that my blood sugar goes up if I exercise or if I do physical work around the house or both. For instance, here’s this morning’s workout (only body weight lifting):

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First column after time is Keto Mojo (home); then Keto Mojo (work); then ketonix; then blood sugar; then notes.

An about 10 point rise in blood sugar isn’t unusual. But this is not the “bad” glycation being caused by excessive sugar intake.

Consider the following too. These are from my FreeStyle Libre CGM. Saturday, I went jogging, then worked on the house all day. Sunday, we went to church, came back, and I worked on the house all day. Tuesday morning, I went to the gym. Monday and Wednesday were no workout days and were primarily sitting at work. Note that every day that involves exercise causes higher glucose for some or all of the day (see particularly Saturday and Sunday):

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If I exercise and do work on my house involving physical activity, my average blood sugar is 106 (Saturday); instead, if I sit in my office and do no exercise at all, my average blood sugar is 90 (Wednesday).

Yet, which is healthier overall? I’d argue Saturday, but this will cause a higher HbA1c reading.

Thus, HbA1c, for those of us who are keto and doing any type of “exercise” including working around the house, is not a great marker of health.

Your thoughts?

(Robert C) #2

I do not think HbA1c is necessarily a measure of health. I do not think it is a race to lower numbers equals “healthier” and higher numbers equals “not as healthy”. Especially given your example of being able to lower the number by being motionless.

If you get a 7 or 8 or more - root cause needs to be determined and dealt with (if you are Keto or not).

Down below 5.6, the top of the standard range, (Keto or not) and all is well - you system can handle whatever inputs you have been throwing at it up to now.

So, even if lots of exercise managed to get you to move from 4.9 to 5.0 - still “all is well”.

But, introduce a dietary change (say from Keto to SAD) and you move from 4.9 to 7 - that needs some attention.

#3

I’m never happy with studies that use the A1c test to verify remission or reversal of diabetes for someone utilizing a low carb or keto diet. Why they think measuring a symptom that is being controlled through diet indicates anything about the underlying condition is beyond me. By that measure, medications cause remission and reversal. In both cases, a treatment needs to continue for A1c to stay low.

I often point out the study that claimed A1c failed to diagnose diabetes in 73% of the cases that the OGTT (Oral Glucose Tolerance Test) diagnosed.

(Robert C) #4

Naturally reducing weight and bettering HbA1c with a non-carb non-processed food diet is vastly different from a side-effect ridden set of chemicals forcing specific blood numbers into some targeted range.

Measuring HbA1c does indicate the actual status of underlying condition if it is being manipulated naturally. If on Keto and it goes down - that is a good thing and hormones are reacting naturally. If HbA1c does not go down while on Keto - that could indicate a physical problem in the body.

#5

Symptom. Not condition.

As noted, A1c typically fails to diagnose the underlying condition as diagnosed with OGTT.

If I had a strawberry allergy and avoid strawberries, my lack of allergy attacks is not an indication of the actual status of my underlying condition.

I would agree that as a treatment for the symptom of high blood sugars, it is a vastly different approach and most probably better. But that’s irrelevant to the matter of remission or reversal or cure of the underlying condition.

Because of a keto diet, I no longer need insulin and metformin, and my A1c has ranged from 5.2 to 5.7 for nearly 3 years. But if I would load up on carbs, I would have a reaction and my blood sugar would soar. Just like someone with an allergy to strawberries would have a reaction if they started eating strawberries.

(Y) #6

First, I’d like to say thats comforting. To know I’m not the only one… :smile:

I have several thoughts on this.
But first, a disclaimer - the following are just my observations and my musings on the mechanisms that might underly them.

  1. Blood glucose levels are just one variable in an immensly complicated system and should not be interpreted flatly and out of context.

  2. Glucose is required by the body. Anyone who has learned about controllers and system control knows that tracking and stabiling a parameter will result in perturbations when external stimulus enters the system.
    So there is a big difference between the body generating glucose from storage to supply the energy demands of the body, compared with pushing energy into stores after food enters the body.
    One is anabolic and the other is catabolic.
    Looking at the glucose marker and ignoring all the countless other markers that drive metabolism cant be right.

  3. The assumption that HbA1c is driven by only glucose levels in the blood seems incorrect to me.
    Again this cannot be viewed flatly.
    The body relies on many mechanisms to clear out oxidized elements, and these will differ wildly between people, times, and a host of other parameters which keep changing.

Lets assume for a second that the body will clear out oxidated anr glycated particles from the blood during and after exercise (no proof here but its not an unreasonable assumption), then the same person would have different HbA1c measurements for identical blood glucose intervals which differ in physical activity.

  1. I’ve seen the “system control” effect, or homeostasis attempts with my CGM with similar patterns for both carb intake and exercise, and more interestingly, the differences between a high intensity workout and a low intensity workout.

In the HIW, the body “jumps” with a spike in BC, trying to make sure probably that I can flee the lion without passing out from hypoglycemia, and then slowly (sometimes a couple of hours) takes the time to get back to normal, with a pronounced peak after having rested (looks like the system takes a while to react, while the muscles no longer clear glucose from the blood causing the rise before the fall).

A very interesting phenomenon which has repeated many times for me was that eating, regardless of the food, immediately brought the BG down to normal, even if it was very high.
And im not talkinh about a rise and fall pattern where am insulin response can be inferred.
Its so instantaneous, that it seems as if the body shuts off all the alarms that caused it to pump glucose into the blood, and relax back to normal, almost like saying “ok. Danger’s gone”.
It may very well involve insulin, but not as a result of food being digested. Cant happen in 1 minute, let alone if its keto food which it was.
That was fascinating.

In the LIW, BG behaves very differently.
It might rise slightly at the beginning, but will mostly find the correct point for stability, and maintain that for a period, after which BG will start coming below the normal daily average, and stay there for a long time, even after resting.

(Bacon is a many-splendoured thing) #7

What I’m not sure of is the degree of accuracy of your meter and how that affects things.

For example, I understand that a lot of meters are accurate to within ±20%. That means a reading of 100 could reflect a real value in the range of 80 to 120, a reading of 90 reflects a value between 72 and 108, and a value between 88 and 132. What I don’t know is precisely how to interpret the overlap. But I’m pretty sure that if the overlap is great, there is a good chance the two readings are essentially the same. Of course, the narrower the range of accuracy, the less overlap there’s going to be, and the greater the chance that different readings reflect actual differences in the blood sugar level.

(Joey) #8

@DjinnG This is fascinating stuff … thanks for sharing your observations about high- vs low-intensity exercise and apparent effects on your blood glucose.

The initial HIW spike and immediate plunge upon eating sure sound like the response to a central nervous system-induced hormonal flood. As you suggest, the brain is likely wired to regard the “fight or flight” challenge to be over if you’re now comfortable enough to be eating something.

My blood glucose is often just over 100 when I bother to measure it … especially in the morning, having eaten no food since the previous evening. To @PaulL’s point, I don’t really trust my meter to be particularly accurate (nor precise). I can get +/- 5 mg/dL difference when testing myself twice in a row.

The larger takeaway for me is that if you’re not eating carbs having your blood glucose high enough to give you energy and mental focus is a healthy sign and a real blessing. No sign of hypoglycemia? That’s clearly not an indication of metabolic dysfunction if you’re not eating carbs.

And if you haven’t eaten anything at all (because your last meal was yesterday) and you have “elevated” glucose instead of “low” glucose, you’re even luckier. Gluconeogenesis is working like a charm.

@ctviggen Thanks for the thread that keeps on giving.

(Bacon is a many-splendoured thing) #9

“Remission” or “reversal” are hard to define. I do know that the term “remission” is used with cancer, because they hate to say the cancer is gone, so “remission” in this sense means “we’re not seeing any problems right now.” But I think the word has been in use long enough that, regardless of the medical meaning, the popular meaning has been moving towards “cured.”

My favourite analogy comes from talk by Andreas Eenfeldt a couple of years ago (should still be available on YouTube). He talks about how keto isn’t a permanent “cure” and likens the ketogenic diet to daily showering: we get the benefits of it when we do it regularly, but if we stop showering, sooner or later we are going to become dirty, greasy, and smelly again. He says life is so unfair like that.

As a more serious comment on your post, however, let me just mention that the real problem is not so much how our blood sugar rises when we eat carbohydrate and then falls because of the insulin response, but (1) how much damage the glucose causes when elevated, (2) how much damage the insulin causes when elevated, and (3) how much insulin it takes to get the blood sugar to go down.

The first two of these three points (the damage done) are determined by the sharpness and duration of any elevated level. A rise that is sharp but transient (the medical term for this is “acute”) is probably not going to do much damage, but a long, sustained rise (“chronic”) definitely does damage. So the rise in serum glucose and insulin from one carb-heavy meal is probably not going to do as much damage as the levels resulting from eating a high-carbohydrate diet over a period of years.

The third point above is the question of insulin-resistance, in which cells have down-regulated their insulin receptors, so that it takes more insulin to produce the same effect on blood sugar. The data show that over time, a person with Type II diabetes can reverse his or her symptoms, and my guess is that eventually, over time, the cells that have down-regulated their insulin receptors will up-regulate them again, thus becoming insulin-sensitive again.

But this is not guaranteed. For example, it appears that cocaine addicts whose brains have down-regulated their dopamine receptors never regain their original dopamine sensitivity; in other words, their brain cells do not up-regulate their dopamine receptors, no matter how long after people stop taking the drug (or if the dopamine receptors are up-regulated again, the process takes years, probably decades). So whether cells with down-regulated insulin receptors will up-regulate them again is an open question, so far as I know. But for various reasons, my hunch is that they will. But I couldn’t possibly hazard a guess as to how long that would take.

(Bacon is a many-splendoured thing) #10

You’ve hit on some good points in your post. I just wanted to mention that there is evidence to show that your point is true not only of HbA1C, but also of serum glucose itself. Studies in mice have shown that when their pancreas is incapable of secreting neither glucagon nor insulin, their blood sugar never gets out of control. So there are obviously other mechanisms regulating it, in addition to the glucagon/insulin combination.

Likewise, since we have evolved so that our erythrocytes lack mitochondria and must therefore rely on glucose to keep them fed, our bodies have also evolved to tolerate a certain amount of glycation of our haemoglobin. This is why HbA1C never seems to go much below 5.4 (in American measurements).

I’m not sure I entirely agree with this statement. We treat HbA1C as though it is is a rolling average of our serum glucose readings, but it isn’t really. It is a measure of the glycation of our haemoglobin, which is affected, but not completely determined, by our serum glucose. There are other factors at work, as well. In any case, HbA1C changes so slowly that it is not going to instantly reflect transient spikes in serum glucose.

Your general point, however, cannot be sufficiently emphasised: once we have determined that a particular measurement is a marker for some health condition, efforts to manipulate the marker do not usually deal with the condition that is the real problem.

(Joey) #11

On the HbA1c metric, my understanding is that the underlying assumption is that a red blood cell has an average life of 3 months. Well, the odds of that being true for any particular red blood cell is approximately zero. So we’re talking about a population distribution around this assumed mean… and all the linear-based assumptions that flow thereof.

The chances that applying such an assumed denominator skews measured results strikes me as being extraordinarily high, no?

(Gregory - You can teach an old dog new tricks.) #12

That is so true! Think about the cholesterol thing…

Oh yeah, will just screw big time with your liver metabolism and make your cholesterol go down!

Think about an overwhelming number of drugs that address the symptoms and not the cause.

(Joey) #13

No more dieting. Picture limb removal as a permanent and effective weight loss method.