On 11th March 2020, the world health organization (WHO) declared SARS COV2 (COVID-19) as a global pandemic. It is responsible for more than 180 thousand deaths worldwide.
Studies have proved that in addition to the older age, chronic diseases are risk factors for COVID-19 such as hypertension, diabetes mellitus and cardiovascular diseases .
Studies on the relationship between COVID-19 and diabetes:
After the out break of COVID-19 in Wuhan, a Chinese study on 1099 patients diagnosed with COVID-19, showed that among 173 individuals with severe diseases:
- 23.7% had hypertension.
- 16.2% had diabetes mellitus.
- 5.8% had coronary heart disease.
Another study was also done on 140 patients showed that 12% of them had diabetes .
Complications of COVID-19 with diabetic patients:
Diabetic patients are more likely to catch a wide range of infections. Some studies have investigated the relationship between ACE2 receptors which is a transmembrane glycoprotein exists on human cells through out the body and chronic diseases as diabetes mellitus .
ACE2 was reported to be the surface receptor of SARS-COV2 that is responsible for the entry of virus by the interaction between ACE2 receptors and protein spike of the virus. Studies have also reported that ACE2 receptors are widely expressed in different organ systems as cardiovascular system, kidney, lungs and brain which gives an explanation of the death of COVID-19 patients of multiple organ failure .
Diabetes is considered as a low grade inflammation condition and in COVID-19, it is a high-grade of systematic inflammation causing elevations in the inflammatory markers as D-dimer, C-reactive protein and ferritin .
Mechanisms associated with increased COVID-19 severity in individuals with diabetes.
- Viral load :
The presence of ACE2 receptors in the lungs leads to the entry of the viral particles affecting the lungs.
Individuals with diabetes have increased ACE2 receptor expression because of using specific drugs such as ACE inhibitors, GLP-1 agonists, and statins which in turn may increase ACE2 levels further and the increased level of glucose may be a good condition for SARS-CoV-2 replication.
- Dysregulated Immune Response:
Diabetic patients have low chronic inflammation which leads to a high increase in macrophage and monocyte and T cell recruitment which will cause further inflammations by the overproduction of pro-inflammatory cytokines that will in turn cause damages to the lung infrastructure. The resulting cytokine storm may initiate multiple systemic coagulation.
- Alveolar Dysfunction:
Diabetes is associated with several structural changes to the lung such as the increased permeability of the vasculature and reduced gas exchange. Impaired respiratory function in patients with diabetes may aggravate pulmonary complications, causing an increased need for mechanical ventilation in diabetes patients.
- Endothelial Dysfunction:
SARS-CoV2 can directly infect endothelial cells through the ACE2 receptors present on the endothelial cells. Change of vascular tone causing more vasoconstriction in diabetes patients can aggravate the subsequent organ ischemia, tissue edema, and a procoagulant state during COVID-19 infection.
Diabetic patients are more likely to have hypercoagulation, fibrinolysis markers, and increased platelet activity and adhesion to endothelial wall which will help in creating a favorable environment for thromboembolic events to occur under hyperinflammatory conditions such as SARS-CoV-2 infection. Blood clots can be detected in multiple organs .
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