Prediabetic on Zero Carbs?
Two months ago I asked: “Does Meat Cause Diabetes?”
I deliberately left one aspect out of that article, as it would have made it considerably longer. It deserves a new article instead:
Elevated HbA1c
Diabetes (type 2, T2D, the German language has a colloquial name translating literally to “sugar sickness”) is usually diagnosed through an elevated Glycated protein in blood, used as indicator for the average blood sugar level during the past ca 3 months → more blood value. This value usually describes the average blood sugar over the past 3 months. It is a measurement of the sugar bound to red blood cells (more precisely: to the red blood pigment), known as glycation - and red blood cells usually live for about 3 months.
So how can you become “sugar sick” without eating sugar, and what does that have to do with the “Does Meat Cause Diabetes” article? To find out, we look at the most extreme variant: an elimination diet(1) in which nothing but meat is eaten.
One reason for such a very strict diet can be to uncover food intolerances. If you exclude, for a while, all foods that might trigger an intolerance, you can reintroduce them one at a time and uncover the intolerances quite easily. But permanent forms are possible too - in my experience with astonishing positive effects on health.
Some people who eat this way notice an increase in their HbA1c blood value (the long-term average of blood sugar). Are they heading towards diabetes? What could be the reasons for the increase, given that I have already denied that meat causes diabetes?
The basis for this article
Does Meat Cause Diabetes?
The ‘fact everybody knows’ - that meat causes diabetes - keeps crossing my path. So I went and read the studies, and ended up with the longest reference list of any article here.
Read more →We already learned in that article that the iron store also affects the HbA1c value: when more iron is available, HbA1c rises too, without relevance for the diabetes values (the insulin level does rise as a result, but that rise is irrelevant for a prediabetes diagnosis). We will see that this need not be the only reason for such a change, and how, surprisingly, you can even argue the opposite direction.
Observations
There are people who, on an elimination diet(1) in which nothing but meat is eaten, observe an increase in their HbA1c blood value.
Such a change of diet is not very often accompanied by continuous glucose monitoring - why would it be: this diet has very little effect on the blood sugar level. If you eat no carbohydrates, you don’t expect your blood sugar level to change significantly. And yet the long-term average sometimes goes up…
How Can That Be?
There is always a certain amount of glucose circulating in the human body - in healthy people usually below 100 mg/dl - in other words below 1 g/l - in yet other words: with about 5 l of blood in total, roughly one teaspoon(2). Over time, this ever-present sugar can not only be used as an energy supplier but also react with proteins in its surroundings. This is called glycation(3). One of the reaction products is what gets measured as HbA1c.
You could say that HbA1c measures how many red blood cells have been damaged by “sugarcoating”.
However, lifespan is not controlled by the calendar but by biological processes, so an alternative explanation for the higher value can simply be a longer life for these blood cells: if fewer are damaged, the body has to replace fewer of them. If they live longer, they have more time for glycation - even at a lower sugar load - and naturally the measured value rises then too.
Since T2D is classically detected via HbA1c, a higher HbA1c value is of course an alarm signal. But in an earlier article we already learned about an alternative measurement that can sound the alarm even 10-15 years before HbA1c rises, but is unfortunately rarely carried out:
Type 2 diabetes, and how to raise the alarm much earlier
Insulin, Chapter 3
Even though Type 2 diabetes is often called a ‘sugar disease’: the real elephant in the room is insulin. The good news: patients can help themselves - if they want to.
Read more →That article also touched on the change in the lifespan of red blood cells as another reason, for example, why blood donation can delay a diagnosis - albeit in the opposite direction: if blood was donated some time before the HbA1c determination, the body has sent new, unglycated blood cells into the race. The value measured is then artificially lower than it should be - logical, because the measured value is the ratio of glycated to unglycated proteins, expressed as a percentage.
The same holds, purely mathematically, in the other direction: if red blood cells live longer, they have more time to react with sugar.
Does that mean red blood cells are healthier and live longer on a corresponding diet? Not necessarily. By its nature it is rather difficult to track the age of such cells directly and individually. I have not found any studies that confirm this directly - but the measurement is ultimately a statistical one, and it also depends directly on the lifespan of the red blood cells.
Just One More Thing
Is that all? Of course not: Above I said “More iron -> higher HbA1c”. Naturally, such a statement only holds within the normal ranges (no massive iron deficiency or oversupply). Within these limits, to put it differently once more: more iron ultimately leads to higher HbA1c. In the opposite direction: less iron means red blood cells are formed more slowly, the existing ones are therefore replaced more slowly, and HbA1c can likewise rise by way of their longer lifespan. Interestingly, this happens without any effect on insulin resistance(4).
Just One More Thing
Now then? No, still not: The body cannot store excess protein, and therefore converts it for energy use: into glucose, fats and ketones (the nitrogen from the protein is excreted in the urine). The resulting rise in glucose is, however, demand-driven and not comparable with the massive rise in blood sugar after a meal rich in carbohydrates - nonetheless a factor that has to be taken into account. Protein also raises the insulin level, but much less than carbohydrates do. In the context of the elimination diet mentioned at the start, I would always assume that it is carried out in the context of fat adaptation of the metabolism: moderate protein (as building material), plenty of fat (as fuel).
Just One More Thing
Another mechanism can be used to explain this: on an extremely low-carbohydrate diet, the liver takes over an important share of the carbohydrate supply. At the same time the muscles become fat-adapted, meaning they burn less sugar and more fat. As a result, glucose is available to the cells that actually depend on it (Which ones are those?). If the liver does not reduce its output because it “wants” to keep supplying the muscles too, the blood sugar level rises - which of course has an effect on HbA1c. This physiological insulin resistance of the muscles is, however, something entirely different from the insulin resistance in T2D or prediabetes.
Conclusion
Anyone who fears they have or might develop T2D is much better informed if the fasting insulin level is measured, or the real average blood sugar: that requires regular measurement - and anyone who doesn’t want to prick their finger regularly will these days use a continuous monitoring device. If these measurements are consistently in the low range, there is probably an all-clear - no matter what the HbA1c measurement says.
By measuring fasting insulin directly, we can therefore distinguish between the two extremes: an elevated average blood sugar due to a chronically high insulin level (T2D or prediabetes) versus one of the other effects that simply occur with a statistical measurement, or that have another physiological explanation in the metabolism.
What we have learned: variations in HbA1c do not necessarily point to a disturbed blood sugar level, but it is a value that depends on many influencing factors. Of course there are unambiguously diabetic HbA1c values, but especially in the transitional range, and on a diet that is non-conforming to the guidelines with extremely few carbohydrates, these other factors potentially carry considerably more weight than in the population average on a carbohydrate-centred diet.
A classic piece of advice is to avoid foods and ingredients to which the body reacts with intolerance - ketogenic diets and a corresponding elimination diet avoid carbohydrates very effectively. What applies to other intolerances applies here too:
If you eat no carbohydrates, it is hard to demonstrate a carbohydrate intolerance(5).
If someone claims you do anyway, it may very well be that they simply looked at a value that is unsuitable in this case.
