Does Covid-19 cause diabetes?

Diabetes is a chronic disease that already affects more than 400 million people around the world and more than 5 million people in Spain.

Diabetes mellitus is characterized by an elevation of glucose levels in the blood caused mainly by a defect in the action or secretion of insulin by the beta cells of the pancreas. This can lead to complications that affect the retina, kidney, nervous system or heart, among others.

During the current covid-19 pandemic, it has been shown that the disease, caused by the SARS-CoV-2 virus, is not a mere infectious clinical picture with respiratory involvement. It is a pathology capable of producing a series of subsequent negative effects on the health of some of the patients who have suffered it.

These effects, in addition to respiratory sequelae, include a whole set of consequences at the cardiac, renal and even neurological level. Likewise, recent data have confirmed a close association between SARS-CoV-2 infection and diabetes mellitus.

Covid-19 and diabetes, cause or effect?

The relationship between these two diseases appears to be bidirectional. On the one hand, it is widely demonstrated that diabetes mellitus is a poor prognostic factor in the evolution of covid-19.

Diabetics infected with SARS-CoV-2 have a higher risk of developing severe pneumonia, higher rates of hospital admissions, and higher mortality than non-diabetic subjects infected with SARS-CoV-2.

One recent meta-analysis showed that diabetes increases 2.3 times the risk of severity and 2.5 times the risk of mortality associated with covid-19.

On the other hand, although the main causes of diabetes are widely known and are mainly related to lifestyle habits (type 2 diabetes mellitus) or the destruction of pancreatic beta cells by our own immune system (type 1 diabetes mellitus), recently a possible association between SARS-CoV-2 infection and the development of diabetes.

The data obtained so far seem to indicate that covid-19 could be the cause of the increase in sugar levels in the blood of affected patients and therefore of the appearance of diabetes mellitus.

The ways in which covid-19 can be related to the onset of diabetes are several:

Cytokine storm effect

Covid-19 produces a storm of pro-inflammatory cytokines such as interleukin 6 or IL-6 and IL-1beta, which have been shown to are related to the establishment and development of type 2 diabetes mellitus.

Insulin-producing cell infection

On the other hand, in patients with covid-19, direct damage is observed on the pancreatic beta cells that produce insulin. The virus infects these cells that have the ACE2 membrane molecule on their surface, using it as key to enter inside.

The cells responsible for the production of insulin express this molecule even in greater quantity than the cells of the lung. In this way, the infection would reduce both its number and its functionality, which has as consequently a decrease in insulin production. It is estimated that up to 30% of patients with severe covid-19 could develop diabetes.

Induction of autoimmunity

As with other viral infections, infection of insulin-producing cells by SARS-CoV-2 can induce a autoimmune response against them. This could cause the immune system to mistakenly attack them, destroy them, and cause type 1 or insulin-dependent diabetes.

Increased stress

Covid-19 increases stress throughout the body, which is accompanied by a increased production of stress-related hormones such as glucocorticoids, secreted by the adrenal glands. These hormones have among their multiple effects the elevation in blood glucose levels (hyperglycemia).

Therapeutic use of glucocorticoids to treat cytokine storm

To avoid the cytokine storm that occurs in covid-19, which is one of the main causes of the worsening and poor prognosis of the disease, glucocorticoid-type anti-inflammatory drugs are often used.

But these drugs are compounds similar to natural stress hormones. Therefore, its use can also trigger a elevation of blood glucose levels, in the same way that occurs when the glucocorticoids themselves are increased by stress.

In conclusion, the appearance of diabetes in patients who have suffered covid-19 could be added, if subsequent studies confirm it, to the long list of pathological sequelae caused by this pandemic.

This would further increase the already high socioeconomic and biosanitary cost of this disease. A detailed clinical study of each case and the choice of an appropriate treatment for the specific situation of each patient would help reduce this impact and the possible development of diabetes.

Antonio J. Ruiz Alcaraz, Professor of Immunology at the University of Murcia and researcher of the IMIB Innate Immunity Group, University of Murcia; Bruno Ramos Molina, IMIB Principal Investigator and Honorary Collaborating Professor of Biochemistry at the University of Murcia, University of Murcia; Maria Antonia Martinez Sanchez, Predoctoral Student Dept. of Biochemistry and Molecular Biology B and Immunology. Nutritionist in the Obesity and Metabolism group at IMIB, University of Murcia Y Mercedes Ferrer Gomez, Head of the Endocrinology and Nutrition Section, University of Murcia

This article was originally published on The Conversation. read the original.

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