Sugar and COVID-19

A pandemic disease COVID-19 is brand-new for the science, it often takes years to prove an association of the risk factors and conduct a confirmatory study, but now there is no time to be lost. I am in quarantine now, and monitor over various facts about COVID-19, and according to them, “an inference about the association between the sugar level in the blood and an infection” stands out. The only reason for my writing this post is that I truly believe this information may save lives: lives of my friends, their friends, and their relatives.

corona virus

Disclaimer: the article is not about medicines or treatment methods, it reflects the facts how rationally it is important to follow recommendations about the activity and added sugar, according to the observed worldwide associations between the high sugar level in the blood and disease severity. I believe, that the British National Healthcare Service, NHS, is gold standard, as it recommends 30 g added sugar for adults, 24 g for children at the age of 7 to 10, and 19 g for children at the age of 4 to 6.

For now, we have heard a lot about people with chronic diseases, having a higher level of the death rate after COVID-19, and people with diabetes. According to WHO, diabetes mellitus is a chronic metabolic disease, characterized by the high level of glucose in the blood (or sugar in the blood). A glycation of a great amount of proteins happens in the body, and it means that “small bits of sugar are attached to the big molecule surface of protein in different places”. One of the most common proteins in the blood is hemoglobin (Hb), and a degree of Hb glycation (i.e. the amount of sugar on its surface) is often measured to confirm diabetes mellitus. It makes sense, because people with diabetes have a higher sugar level in the blood, and their hemoglobin is more “covered with sugar” compared to healthy people. In fact, diabetic patients, who properly control the sugar level in the blood, have a decrease of the hemoglobin glycation. Let this fact sink well into your mind.

Biochemistry moment. The sugar in the blood is just a glucose level, and fructose should be converted into glucose in the liver at first, and both of them are quickly absorbed into the upper parts of the intestine and quickly reach the blood flow. Glycation (more details on Wikipedia) is a spontaneous process of attachment of the glucose and fructose remnants to fats and sugar. The excessive glycation of proteins is harmful, because it affects their structural properties and leads to the formation of the advanced glycation products, cross-linked proteins, and the walls of the blood vessels become harder because of the collagen glycation.

We should also know, that hemoglobin is a protein for an oxygen transport from small saccules (alveoles) in the lungs into all cells of the organism. Hemoglobin includes iron atom (and iron binds oxygen). Hemoglobin is found in red (due to iron) blood cells (erythrocytes), and these cells are regenerated every 4 months with hemoglobin, and therefore glycated hemoglobin shows our “averaged sugar in the blood” within the past 3-4 months. As its amount is high in the blood, and it can be easily distinguished, it becomes a convenient marker, and it is not connected with the diabetes complications directly.


Any infection, be it bacterial, or viral, is, in fact, a very fast replication of the infectious agent. The bacterial cells are generated by means of the cell fission, i.e. they double in every cycle. Viruses are pieces of information, covered with proteins, and they penetrate into the cells and “implement” their program into the cellular mechanism of our own cells, i.e. our own cells produce more and more copies of the virus. The cell dies at some point, and all copies go to the body to infect even more cells. It may happen faster than the bacteria replication, because the virus is smaller and is faster collected.

The speed of the replication depends on the resource availability to create a great amount of viruses. Viruses have evolved within million years, they learned to steal glucose from our own cells for their building, accelerating the metabolism of the infected cell, and our infected cells accelerate a consumption of sugar from the blood. If there is more sugar in the blood, the production will be faster.

Other cells of our body are also accelerated to fight with the virus and use sugar to prepare the immune response. A production of cytokines is a part of this immune response. It is well known, that a fast immune response may affect the tissues trying to save the body. It is called as cytokine storm. It may cause bleeding in the tissues with the infection. Doctors also slow down cytokines with the help of medications (inhibitors) in order to save our body from our own immune response.

Scientists have recently studied a common influenza, and showed that patients with infection have a higher sugar level in the blood than normal. It means that sugar is a risk factor of infecting.

That looks promising. I have followed several friends on the social media, who had weak symptoms, and they had enough antibodies after the recovery from COVID-19 in order to donate blood for sick patients. I know, that some of them are on a diet with sugar rationing. There is more and more sense in the thoughts.

A group of doctors in the USA have also found this association. Their study showed, that the death rate is by four times higher in people with diabetes and ill-managed hyperglycemia (high sugar level) who are hospitalized for COVID-19. 42% of patients, who did not have a provisional diagnosis diabetes before the hospitalization, but they developed hyperglycemia during the hospital stay, died. Experts state, that it is now very important to restrict the number of the office visits for people with diabetes in order to protect oneself and health care professionals, and also to reduce the load on the health care system.

Adam M. Brufsky, a professor of medicine in Pittsburgh, indicates another interesting fact about COVID-19 and sugar. He states that COVID uses specific proteins on the surface of our lungs. This protein is called as ACE. The protein is common on the surfaces of the lung and pancreas gland cells. He describes – if this ACE protein is covered with sugar, the virus can easily attach to it. As the virus affects the pancreas gland (due to ACE protein on the surface), more sugar appears in the blood (the very hyperglycemia). Why? The infected pancreas gland produces less insulin, and sugar is not absorbed into the cells from the blood flow. This additional sugar glycates more ACE proteins in the lungs and pancreas gland. This is a real chain reaction, and sugar stood at the origins of it.

The assumption of professor Brufsky is based on the observation over SARS (the epidemic caused by the virus similar to COVID-19 in 2003), where the above-mentioned mechanism of the pancreas gland lesion is well known. Now doctors also observe hyperglycemia in patients with COVID. The drug hydroxychloroquine is now more and more used, because it stops the glycation, and sugar is not attached to proteins, i.e. the drug stops the chain reaction.

Why is the sugar coating, glycation, so important for the virus? I see it as a jam: the more sugar there is on the surface of the proteins and ACE, the easier they will stick to each other. Just like jam that stuck to the table.

Hemoglobin, Lung Injury, and Sugar

I talked to my friend Vardan, a brilliant cardiac surgeon, yesterday, and this conversation made me think about the sugar and collect this information. Vardan is one of those doctors who got sick at work, and he is a patient within the past 20 days. When he saw a computer tomography, he decided to make a video for the family, as it was bad. His exact words were: “It is not a pneumonia, we call it as a broken hemoglobin, but you know better.”

Yes, the last grant project that I did in the European Research Institute for the Biology of Ageing (ERIBA), was dedicated to the protein oxidation, glycation, and ageing. We believe, that a high blood sugar level influences on the ageing, the sugar remnants influence on the molecular level inside and outside of the cells, on our perfect machines of life. As well as hemoglobin and ACE, every protein in the cell is slowly covered with sugars. Just imagine gear inside the clock, covered with the dust; the clock will stop at some point.

Coming back to hemoglobin, the main problem with COVID is a reduced functional space in the lungs. The lungs may be imagined as a turned over tree, where trachea is the body of a tree, and lungs are branches that branch out and become smaller. The smallest branches contain some air-pockets – alveoles, the size of which is just 0,2 mm, they have very thin walls 0,02 mm serving as a barrier between them. There are 600 million alveoles in the lungs. The oxygen-exchange happens in the walls of alevoles, where the thinnest blood capillaries go. Hemoglobin takes oxygen from the air and transfers it through the body. These are the cells of alveoles, that are infected during COVID-19.


Now, imagine that a high sugar level in the blood causes cytokine storm, and the immune system attacks the thinnest walls of alveoles, as a result, the blood flows out. When the blood contacts the air, it starts coagulating – proteins (mainly fibrinogen) stick to each other. This is a normal process, and it protects us against bleeding, when we have a cut, the coagulated part of the blood is called a blood clot.

Diabetic patients have a higher risk of thrombosis, a disease when the blood clots appear in the blood vessels. In fact, we know a lot about the clots inside the large vessels, or when the blood vessel is affected. Moreover, it is doubtless that there is hemoglobin in the alveoles as an additional booster for the coagulation, when it comes out of the affected blood cells. Some studies about this issue have been recently generalized. It sounds like the same is the case for the complications during COVID.

The more viral agents are in the lungs, the more chances there are to get internal bleeding and blood clots. The blood gets thicker, and there is less space for the oxygen-exchange, and a patient dies of the low content of the oxygen in the blood. If proteins are covered with sugar, they stick even better (analogy with jam). There are many evidences of the increased thrombosis in the patients with diabetes. The reason is sugar.


Another recent assumption is that virus COVID also attacks hemoglobin, or more precisely its part called as porphyrin. Porphyrin is a ring inside hemoglobin, which keeps iron. Isn’t it amazing? The virus breaks our proteins, a transport of oxygen, and the broken protein stick more to the clots in the lungs, and as a result, there is a ground glass opacity on the CT scan. Our blood with the broken hemoglobin transports less oxygen, and the blood clots reduce the available space for the oxygen exchange in the lungs. Tell you what, when hemoglobin is covered with sugar, the virus easily sticks to it and breaks the protein. The viral proteins are also covered with sugar, and therefore the analogy with the jam is traced.

The last confirmation is widely debated on the internet as a work with wrong methods, it is better to leave it as an assumption, but there is enough data in order to be confident that a high sugar level in the blood is a predictor of the complications during the COVID.

Everything falls into place

If you have a low sugar level in the blood, the virus has fewer material for the replication, it is more difficult to cause cytokines storm and bleeding, the affection of the pancreas gland will not lead to the higher blood sugar level. Even if the bleeding is started, the blood clots are less sticking. Moreover, it is conceivable that it is difficult to the virus to kill hemoglobin containing oxygen. It seems highly probable, that you breathe and have enough time for your immunity to defeat the virus.

If your blood sugar level is high, the virus has a lot of materials for the replication, the cytokines storm is easily caused, and bleedings are started, the pancreas gland is affected even more. Insulin is not produced, and there is more sugar in the blood and more sticking proteins. When bleeding is started, the blood clots grow in size and become more sticky. Moreover, there is a high risk that the virus easily breaks hemoglobin, transferring oxygen. It is known that the speed of the chain reaction is several hours in these patients, and their normal condition quickly becomes critical; the oxygen supply is required.

Questions you should think about

What food do people get in the hospitals? Does it increase the sugar level in the blood? I know what the food is after my work inside and with the hospitals in Great Britain and the Netherlands. And I know that the bone broth would be the best replacement of that food.


As you know, the survived patients have fibrosis. This is the same clots in the lungs that become a connective tissue, and it makes persons disabled for the life term. The clots may, in fact, be dissolved in time, during lysis, but, as we know, the lysis process gets worse in patients with diabetes (or high sugar level) due to one and the same jam.

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