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COVID-19, Obesity and Diabetes

Maryam Shapland, MD
Maryam Shapland,

Vice President and Medical Director
RGA U.S. Mortality Markets

As COVID-19 continues to spread worldwide, characteristics of a country’s population may be associated with clinical features and outcomes of the disease. The higher case-fatality rate in Italy compared to China, for example, has been attributed to its older population8. However, some authors have argued that the increased prevalence of obesity in older adults in Italy may also account for the differences in mortality between the two countries.2

Obesity has also been linked to severe coronavirus disease in Americans. According to the CDC1, in 2017-2018, the prevalence of obesity in the United States was 42.4%. Americans have a high burden of severe obesity, as 9.2% of the population have a BMI>40 kg/m 2. Findings from recent studies have shed some light on the intersection of COVID-19 and obesity: 

  • Per the March MMWR11, 48.3% of adults hospitalized with COVID-19 were obese. Remarkably, of the admitted patients aged 18-49, 59% were obese. In older patients, 49% of those aged 50-64 and 41% of those aged 65 years and older were obese.
  • A retrospective analysis7 of BMI stratified by age was performed in 3,615 COVID-19-positive patients presenting to a large academic hospital system in New York City. This study showed that compared to patients in the same age category with a BMI <30:
    • Patients aged <60 years with a BMI of 30-34 were two times more likely to be admitted to acute care and 1.8 times more likely to be admitted to critical care.
    • Patients aged <60 years with a BMI ≥35 were 2.2 times more likely to be admitted to acute care and 3.6 times more likely to be admitted to critical care.
  • A retrospective case series5 of 393 adults admitted to a community hospital in New York City with confirmed COVID-19 infection found that 35.8% of admitted patients were obese. Of the patients who required invasive mechanical ventilation, 43.4% were obese.

Obesity was recognized as an independent risk factor for complications from H1N1 infection during the 2009 pandemic.4 Although it remains to be seen whether obesity is an independent risk factor for severe COVID-19 illness, anatomy and pathophysiology indicate this may be the case. Obesity exerts a mechanical effect on lung physiology, and adipose tissue can function as an endocrine organ producing systemic inflammation and effecting central respiratory control.12 This can then lead to diseases such as obstructive sleep apnea, restrictive lung disease, obesity hypoventilation syndrome, and airway inflammation, which subsequently exacerbates underlying asthma and COPD. Intubation and ventilation of obese patients are often complicated by unaccommodating anatomy, poor lung function, and smaller lung volumes. An increased work of breathing places additional strain on already impaired cardiac and pulmonary functions.12

Persons with obesity are also at high risk by virtue of the chronic diseases that obesity drives.4 Not only does chronic hyperglycemia lead to an immunodeficient state and increased pulmonary infection risk, but patients with diabetes exhibit more severe disease when infected with respiratory viruses. In fact, during the 2009 H1N1 pandemic, the presence of diabetes tripled the risk of hospitalization and quadrupled the risk of ICU admission once hospitalized.9

Researchers have hypothesized3 that diabetic patients are at increased risk for COVID-19 infection as human pathogenic coronaviruses bind to their target cells through angiotensin-converting enzyme 2 (ACE2), which is expressed by epithelial cells of the lung, intestine, kidney, and blood vessels. The expression of ACE2 is substantially increased in patients with type 1 or type 2 diabetes, facilitating infection with COVID-19. Once infected, it has been shown6 that patients with diabetes and no other comorbidities were at higher risk of severe pneumonia, excessive uncontrolled inflammatory response, and hypercoagulable state, which are all associated with dysregulation of glucose metabolism. In a recent study10, the authors noted that among 1,382 COVID-19 patients, diabetes was the second most frequent comorbidity found. Diabetic patients had an increased risk of ICU admission (OR 2.79); and in 471 patients analyzed for secondary outcome, those with diabetes had a higher mortality risk (OR 3.21). In the March MMWR11, diabetes was present in 28.3% of adults hospitalized with COVID-19 in the US.

Given the complex interplay, much of which is still unclear, between SARS-CoV-2 and obesity, and its associated conditions such as diabetes and pulmonary disease, it is evident that the management of obese patients with COVID-19 will continue to be a challenge as this pandemic develops.

Underwriting Takeaways

  • In the US, obese adults of all ages are at higher risk for severe and critical COVID-19 disease.
  • It appears that the effect of obesity on the severity of COVID-19 disease skews towards a younger population, with disease severity worsening as BMI increases.
  • It is still undetermined to what extent obesity is an independent risk factor or a confounding variable for severe COVID-19 disease. However, the metabolic and pulmonary sequelae of morbid obesity have been shown to increase the risk and complications of respiratory infections.
  • Diabetic patients appear to be at increased risk for infection and worse prognosis from COVID-19 via ACE2 expression and an excessive inflammatory response.


  1. Centers for Disease Control and Prevention: Adult Obesity Facts.
  2. Dietz, W. and Santos-Burgoa, C. (2020), Obesity and its Implications for COVID-19 Mortality. Obesity. doi:10.1002/oby.22818
  3. Fang L, Karakiulakis G, Roth M. Are patients with hypertension and diabetes mellitus at increased risk for COVID-19 infection? Lancet Respir Med. 2020;8(4):e21. doi:10.1016/S2213-2600(20)30116-8
  4. Finer N, Garnett SP, Bruun JM, COVID-19 and obesity, Clinical Obesity, (2020). Wiley Online Library
  5. Goyal P, Choi J, Pinheiro L et al. Clinical Characteristics of Covid-19 in New York City. NEJM. April 17, 2020. DOI: 10.1056/NEJMc2010419
  6. Guo, W, Li, M, Dong, Y, et al. Diabetes is a risk factor for the progression and prognosis of COVID-19. Diabetes Metab Res Rev. 2020; e3319.
  7. Lighter J, Phillips, M, Hochman S, et al. Obesity in patients younger than 60 years is a risk factor for Covid-19 hospital admission, Clinical Infectious Diseases, ciaa415,
  8. Onder G, Rezza G, Brusaferro S. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. Published online March 23, 2020. doi:10.1001/jama.2020.4683
  9. Puig-Domingo, M., Marazuela, M. & Giustina, A. COVID-19 and endocrine diseases. A statement from the European Society of Endocrinology. Endocrine 68, 2–5 (2020).
  10. Roncon L, Zuin M, Rigatelli G et al. Diabetic Patients with COVID-19 infection are at higher risk of ICU admission and poor short-term outcome. Journal of Clinical Virology. Available online April 9, 2020.
  11. US Department of Health and Human Services/Centers for Disease Control and Prevention. Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019-COVID-NET, 14 States, March 1-3, 2020. MMWR/April 17, 2020/Vol 68/No 15
  12. Zammit C, Liddicoat H, Moonsie I, Makker H. Obesity and respiratory diseases. Int J Gen Med. 2010; 3:335–343. Published 2010 Oct 20. doi:10.2147/IJGM.S11926