COVID-19 Risk Factors – Diabetes

There are certain factors that put particular groups of people at higher risk of experiencing severe disease if infected by SARS CoV-2. Click here for an overview.

The association between non-communicable disorders (NCDs) and more severe COVID-19 symptoms is consistent worldwide; those with underlying NCDs are more vulnerable to experiencing severe complications following infection with SARS CoV-2. 

Some of the most prevalent NCDs include type 2 diabetes, hypertension, cardiovascular disease, chronic lung conditions, chronic kidney disease, chronic liver disease, and cancer

This article covers diabetes.

What is Diabetes Mellitus (DM)?

Patients with diabetes are unable to properly regulate their blood glucose levels due to insufficient insulin production or reduced insulin sensitivity. Lack of insulin, or the inability of cells to respond to insulin, results in high blood glucose levels, known as hyperglycaemia

Under normal conditions, one of insulin’s many functions is to signal your body to activate white blood cells, which are the main cells in our blood and lymph nodes that fight infections. Therefore, when the body is unable to produce sufficient amounts of insulin, the immune system may be compromised as a result, putting the individual at risk of infection. A compromised immune system will be less able to control the spread of, and manage the symptoms associated with, invading pathogens such as SARS CoV-2.

Why does diabetes increase the risk of COVID-19 complications?

  • Efficient viral entry into cells. The ACE2 receptor is the enzyme that is allowing SARS CoV-2 to infect the cells of the body. Increased expression of ACE2 correlates with increased viral uptake by the cells of the body. Preliminary data suggests that patients with diabetes might have an increased expression of ACE2 in the lungs; however further work is required to validate this. 
  • An inability to efficiently clear the virus. Patients with diabetes seem to be less able to clear the virus once it enters their body. 
  • Compromised immune response. The body’s immune system relies on its ability to metabolise glucose as a form of energy. The inability of diabetics to regulate glucose, results in perpetual activation of the immune system, which causes a state of immune exhaustion. This can, in turn, compromise the extent to which an individual is able to fight infections
  • Increased susceptibility to hyperinflammation. A further consequence of having a compromised immune system means that people with diabetes may be more susceptible to an intense inflammatory response upon exposure to SARS CoV-2. Normally the immune system is composed of cells that function to dampen an acute inflammatory response. These cells are also dysfunctional in diabetics, therefore, it is more difficult to maintain immune homeostasis, resulting in an increase in inflammatory mediators (known as cytokines). The physiological consequence of this is a ‘cytokine storm’, which can, in severe cases, lead to multiorgan failure.  
  • Comorbidities. The prevalence of obesity, cardiovascular disease and hypertension is high in patients with diabetes. Furthermore, being in a hyperglycemic state puts pressure on the body’s organs, including the heart, kidneys, and nervous system, which become susceptible to damage. Individuals with type 1 or type 2 diabetes are, therefore, at increased risk of developing additional health complications, such as cardiovascular disease, renal disease, and peripheral nerve damage. This, in turn, makes them more susceptible to experiencing an adverse response to infections and other external pressures.

Patients with well controlled diabetes are at lower risk of experiencing diabetes-related complications following SARS CoV-2 infection. 

I have diabetes, what should I do?

If you are diabetic, it is important to keep taking your medications. To date, there have been no supply-related issues. Those who are on insulin replacement therapy should monitor their body’s sensitivity to insulin which will determine the appropriate dose of insulin to take in order to avoid entering a hyper- or hypoglycaemic state.

In addition to this, make sure that your overall health is as good as possible; your diet should be well-balanced and nutritious, and you should stay active, partaking in regular exercise


  • “How COVID-19 Impacts People with Diabetes.” American Diabetes Association,
  • Muniyappa, Ranganath, and Sriram Gubbi. “COVID-19 Pandemic, Coronaviruses, and Diabetes Mellitus.” American Journal of Physiology-Endocrinology and Metabolism, vol. 318, no. 5, 26 Apr. 2020, doi:10.1152/ajpendo.00124.2020
  • “People Who Are at Higher Risk for Severe Illness.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 14 May 2020,
  • Yang, Jing, et al. “Prevalence of Comorbidities and Its Effects in Patients Infected with SARS-CoV-2: a Systematic Review and Meta-Analysis.” International Journal of Infectious Diseases, vol. 94, 12 Mar. 2020, pp. 91–95., doi:10.1016/j.ijid.2020.03.017.
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