Covid-19 and Diabetes

COVID-19 is the illness caused by the novel coronavirus, SARS-CoV-2 virus. The virus is highly contagious and causes a cold-like disease.  

Most people infected with the virus will only experience mild to moderate symptoms. Complications such as pneumonia are more common if you have certain underlying health conditions.

Cardiovascular disease, diabetes, hypertension and chronic respiratory disease are associated with increased severity and mortality in COVID-19 patients [1].

Are people with diabetes more vulnerable to infections?

Diabetes increases the risk of complications from viral and bacterial infections. Potentially life-threatening complications, such as pneumonia, are more likely to develop in people with diabetes if they catch common infections such as the seasonal flu [2].

During the previous coronavirus epidemics, scientists also found that diabetes was a risk factor for SARS [3] and MERS-CoV [4].

Recent studies looking at the effect of the SARS-CoV-2 virus found that patients with diabetes are more likely to require hospitalisation for COVID-19 and to need treatment in intensive care [5]. Mortality is also higher in people with diabetes than the general population [6], so people with diabetes must take extra precautions to avoid catching COVID-19.

People with diabetes may also be more likely to have other health conditions such as high blood pressure and obesity, which are also risk factors for COVID-19 [7].

What is diabetes?

Diabetes is a metabolic condition associated with abnormally high blood glucose levels. In healthy people, the hormone insulin is released after a meal to help muscle and fat cells absorb glucose, removing sugars from the blood. Diabetes occurs when your body is unable to respond to insulin or doesn’t make enough insulin.

Type 1 diabetes is an autoimmune condition caused by the immune system attacking the cells in the pancreas that release insulin. This prevents the body from producing enough insulin to help cells absorb glucose in the blood and subsequently requires treatment with insulin to manage the condition.

Type 2 diabetes is characterised by insulin resistance; this is when the body no longer responds to insulin as well as it should. The risk of developing type 2 diabetes is reduced by lifestyle factors such as exercise and healthy eating.

Why are infections more severe in people with diabetes?
People with diabetes are more susceptible to developing complications from infections for several reasons. High glucose levels are found not only in the blood but also in the body’s tissues; this is called a hyperglycaemic state.

Not only can viruses and bacteria grow more quickly in a hyperglycaemic environment, but the immune response is altered in diabetes. The function of immune cells, such as monocytes and neutrophils, is impaired, and it is more challenging for the body to resolve infections [8, 9].

Scientists have also suggested that a low level of chronic inflammation in diabetes may result in an excessive inflammatory response [10]. Chronic inflammation may further impair the immune response when the body is fighting off an infection [11].

Diabetes health checks

The risk of complications from infections can be reduced by tightly controlling your glucose levels [1]. The best way to manage your glucose levels is by measuring the level of glucose in the blood. If you think you have prediabetes or diabetes, order a test today to see if your glucose levels are in check.

Our ‘Diabetes’ health checks offer a comprehensive range of tests, including quick and straightforward finger-prick tests that can be performed easily at home.


1. Aylward, Bruce (WHO); Liang, W. (PRC). Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). WHO-China Jt. Mission Coronavirus Dis. 2019 (2020).
2. Hong, K. W. et al. Clinical courses and outcomes of hospitalized adult patients with seasonal influenza in Korea, 2011-2012: Hospital-based Influenza Morbidity and Mortality (HIMM) surveillance. J. Infect. Chemother. (2014) doi:10.1016/j.jiac.2013.07.001.
3. Yang, J. K. et al. Plasma glucose levels and diabetes are independent predictors for mortality and morbidity in patients with SARS. Diabet. Med. (2006) doi:10.1111/j.1464-5491.2006.01861.x.
4. Alraddadi, B. M. et al. Risk factors for primary Middle East respiratory syndrome coronavirus illness in humans, Saudi Arabia, 2014. Emerg. Infect. Dis. (2016) doi:10.3201/eid2201.151340.
5. Li, B. et al. Prevalence and impact of cardiovascular metabolic diseases on COVID-19 in China. Clinical Research in Cardiology (2020) doi:10.1007/s00392-020-01626-9.
6. Zhou, F. et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet (2020) doi:10.1016/S0140-6736(20)30566-3.
7. Lighter, J. et al. Obesity in patients younger than 60 years is a risk factor for Covid-19 hospital admission. Clin. Infect. Dis. (2020) doi:10.1093/cid/ciaa415.
8. Khondkaryan, L., Margaryan, S., Poghosyan, D. & Manukyan, G. Impaired Inflammatory Response to LPS in Type 2 Diabetes Mellitus. Int. J. Inflam. (2018) doi:10.1155/2018/2157434.
9. Insuela, D., Coutinho, D., Martins, M., Ferrero, M. & Carvalho, V. Neutrophil Function Impairment Is a Host Susceptibility Factor to Bacterial Infection in Diabetes. in Cells of the Immune System [Working Title] (2019). doi:10.5772/intechopen.86600.
10. Bornstein, S. R., Dalan, R., Hopkins, D., Mingrone, G. & Boehm, B. O. Endocrine and metabolic link to coronavirus infection. Nat. Rev. Endocrinol. (2020) doi:10.1038/s41574-020-0353-9.
11. Hu, R., Xia, C. Q., Butfiloski, E. & Clare-Salzler, M. Effect of high glucose on cytokine production by human peripheral blood immune cells and type I interferon signaling in monocytes: Implications for the role of hyperglycemia in the diabetes inflammatory process and host defense against infection. Clin. Immunol. (2018) doi:10.1016/j.clim.2018.06.003.
12. Critchley, J. A. et al. Glycemic control and risk of infections among people with type 1 or type 2 diabetes in a large primary care cohort study. Diabetes Care (2018) doi:10.2337/dc18-0287.

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