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ADA 2021: Are Patients with Obesity or Diabetes at Increased Risk for Severe COVID-19?

Jul 20, 2021
Editor: Steve Freed, R.PH., CDE

Author: Ashley Ball, PharmD Candidate, LECOM-School of Pharmacy

Analysis of the role obesity or diabetes play in severity finds that for every increase of a BMI unit, there was a 5-15% excess risk of developing severe COVID-19.

Age is the number one risk factor for severe COVID-19. For example, a person over 80 years old has a 70-fold risk of getting a severe case of COVID-19 relative to a 40-year-old. Other significant risk factors are male sex, South Asian or African descent, prior heart failure (HF), stroke, and renal dysfunction. Recently, the possibility of an association between diabetes and obesity with severe COVID-19 has arisen. 


To explore if obesity and diabetes are risk factors for severe COVID-19, investigators reviewed over 500 studies, including a dozen meta-analyses. The investigators found that not only are obesity and diabetes significant risk factors for severe COVID-19 but that they are also much more strong risk factors than some of the cardiovascular (CV) conditions that are known to be risk factors. Investigators discovered that patients with diabetes account for the leading and disproportionate excess of COVID-19 mortality worldwide. The studies were consistent in their findings. They found that for every increase of a BMI unit, there was a 5-15% excess risk of severe COVID-19. With diabetes, investigators found that people with T1DM have a two-to-four-fold increase and that people with T2DM have a one and a half to fivefold increase in the risk of severe COVID-19. 

T1DM becomes a risk factor at age 40 or 50 years old. The risk with age may be due to the decades of renal damage and microvascular disease from chronic hyperglycemia. With T2DM, the risk was high at a young age, likely because of the early onset of obesity.  

Studies found that the risk of severe COVID-19 in patients with obesity is much higher than the risk patients with obesity have for the flu or respiratory distress syndrome. Studies showed that higher BMI meant increased risk for hospitalization. The risk increased by 2-4 times as BMI increased from twenty to forty-five. People with a BMI of 35 had a four-fold risk of severe COVID-19 compared to those with a BMI of twenty. The risk of hospital and ICU admission increased linearly with BMI. Death increased with a BMI of 26 and up. At a lower BMI, the increase for death also increased; this skew may be due to the elderly, frail population that early on in the pandemic died in high numbers. Showing causality, the Cleveland Clinic found people who underwent bariatric surgery, losing about 12 BMI units, had a 69% lower risk of hospitalization and ICU admission compared to those that did not have bariatric surgery. 

In concluding that obesity is a causal risk factor of COVID-19 acute infection, the researchers looked into understanding why. They found epidemiological and genetic evidence, historical data, and biological plausibility. People with obesity and excess ectopic fat have decreased cardio-respiratory metabolic reserve making them more susceptible to vascular effects, thrombotic effects, and an impaired metabolic response that increases severity from COVID-19 infection.  

In summation, obesity and diabetes are significant risk factors in severe COVID-19. Future studies are needed to investigate the relationship between fat cells and viral load. In addition, there needs to be more research examining the role that worsening lung function, kidney function, and vascular health have on the severity of COVID-19. There is a clear need for an increase in obesity prevention and management efforts. Likewise, T2DM prevention efforts need to be increased by health care professionals. The complications discussed are consistent with poor control of diabetes, as studies found acute or chronic complications of diabetes increased risk of severe COVID-19. So, the prevention of complications due to uncontrolled T1DM and T2DM needs to be continued and improved. 

Practice Pearls: 

  • Diabetes and obesity have more significant roles than expected in COVID-19 severity. 
  • It is crucial to prevent diabetes complications by optimizing BP, weight, and HbA1c measurements. 
  • Lifestyle modifications are essential for preventing the onset of T2DM and for managing T1DM and T2DM. 


Sattar, Naveed. “Obesity and Diabetes—Risk Factors for Severe COVID-19.” American Diabetes Association (ADA) Virtual 81st Scientific Sessions. June 28. 2021 (Requires ADA Symposium login.) 

Sattar, Naveed, et al. “Obesity Is a Risk Factor for Severe COVID-19 Infection”. Circulation, April 22, 2020. 

Ashley Ball, PharmD 2022 Candidate, LECOM-School of Pharmacy