Diabetes, CVD Tied to Worse Prognosis for COVID-19 Infection

Veronica Hackethal, MD

February 25, 2020

Indications so far are that people with diabetes and other chronic medical conditions, such as cardiovascular disease (CVD), will have a worse prognosis if they become infected with COVID-19, the novel coronavirus that has emerged from China.

There is also evidence that diabetes may increase risk for infection from COVID-19 two- to threefold, independently of other medical problems, such as CVD.

Although more detailed analysis is needed to show a clearly defined connection between conditions such as diabetes and worse prognosis with COVID-19, the statistics suggest that this virus hits hardest among the most vulnerable, ie, the elderly and people with multiple medical problems, especially those with diabetes of long duration that has not been well controlled.

"The message we want to emphasize is that emergencies unmask vulnerabilities in diabetes. The old and the sick are the most vulnerable," Juliana C. N. Chan, MD, told Medscape Medical News in an interview.

Chan is director of the Hong Kong Institute of Diabetes and Obesity at the Chinese University of Hong Kong.

Chan and other experts are therefore calling for diabetes patients, those with CVD, and patients with other chronic medical conditions to be extra vigilant in their efforts to avoid contact with the virus, although they also note that individual responses vary greatly.

In past infectious disease outbreaks, including severe acute respiratory syndrome (SARS) and H1N1 flu, people with diabetes were at increased risk for severe illness and death.

"I don't think it's an overstatement to say that people with diabetes...are at higher risk of developing COVID-19, because the data are suggestive," noted Chan, although she cautioned that longer-term research will give a much clearer picture.

Poor Control of Diabetes a Risk Factor for Infection

Chan was a senior coauthor on a study published last month in Diabetologia, as reported by Medscape Medical News, that found that mortality rates among people with diabetes in Hong Kong have plummeted in recent years ― except for young people, who may be more likely to have poorly controlled diabetes.

And — importantly within the context of the COVID-19 outbreak — although in that study deaths from most conditions such as CVD and cancer decreased among people with diabetes, deaths from pneumonia among people with diabetes remained about the same.

In serious cases of infection, the COVID-19 virus invades the cells that line the respiratory tract and lungs and enters the mucus, causing pneumonia. Severe lung damage from pneumonia can result in acute respiratory distress syndrome (ARDS), which in turn can cause septic shock.

ARDS and septic shock are the main causes of death from COVID-19.

So far, Hong Kong has had only 70 confirmed cases of COVID-19, although the first Hong Kong resident to die from the virus was a 39-year-old man with diabetes. That death was soon followed by a second death ― a 70-year-old man with diabetes and other medical problems, including high blood pressure and kidney disease.

"Our message is to ask people with diabetes to do things early in order to protect themselves and reduce their risk of having problems if anything happens," Chan emphasized to Medscape.

Although the mechanism of this increased susceptibility remains unclear, research suggests that high blood glucose levels may lead to reduced functioning of the immune system.

Not Yet Pandemic, but Virus Has Claimed Many More Lives Than SARS

As of February 25, COVID-19 had infected about 80,000 people and had caused almost 2500 deaths worldwide.

Although the vast majority of these infections and deaths have been in China, there are now pockets of infection in Iran, Italy, Japan, and South Korea, as well as handfuls of cases in many other countries.

The World Health Organization (WHO) yesterday stopped short of calling the outbreak a pandemic but stressed that the status could change at any time.

Although COVID-19 appears to be highly transmissible, only a small percentage of people seem to develop severe illness, and an even smaller number die from the infection.

A recent study of 44,672 confirmed COVID-19 cases that had been reported through February 11 and that were analyzed by the Chinese Centers for Disease Control and Prevention (CCDC) shows that 80.9% of people in China who have been diagnosed with COVID-19 have had mild illness.

So far, the overall case fatality rate (CFR) in China is 2.3% ― less than previous coronavirus outbreaks caused by SARS (CFR: 9.6%) and Middle East respiratory syndrome (MERS) (CFR: 34.4%).

That said, because COVID-19 has infected far more people than SARS or MERS, the newest coronavirus on the block has already claimed many more lives.

This in turn raises the question: who is most at risk for severe illness and death from COVID-19?

Case fatality rates vary by factors such as age, sex, underlying medical conditions, and geography. Outside Hubei province in China, the epicenter of the outbreak, the CFR may be as low as 0.4%, compared to 2.9% within the province.

Case Fatality Rate for Diabetes Is High, but Interpretation Tricky

So far, for all age groups, the highest CFR is among people aged 80 years or older, at 14.8%. CFRs have been higher in people with other medical conditions than in healthy people.

CVD and diabetes top that list, at case fatality rates of 10.5% and 7.3%, respectively, compared to 0.9% for people without any prior disease, according to the aforementioned latest CCDC report.

Before publication of this report, two relatively small case series of patients who had been hospitalized for COVID-19 in Wuhan also suggested that older men with underlying medical problems, especially CVD and diabetes, are more likely to develop severe illness from the virus.

However, experts caution that for COVID-19 and similar infections, several factors may skew the data, making interpretation tricky.

"Cases that are identified tend to be in patients that have more severe illness, compared to younger, healthier individuals who just stay home and don't seek medical care," said Preeti N. Malani, MD, an infectious disease specialist and chief health officer at the University of Michigan Medical School, Ann Arbor.

"This is also the case with individuals who are sick enough to be hospitalized. There are more people with more chronic conditions, including diabetes [among hospitalized individuals]," Malani told Medscape via email.

"In general, diabetes can be a marker of other chronic health conditions like heart disease as well as obesity, which might contribute to the increased risk of infection," Malani added.

"Diabetes is also much more common with age and will continue to be a marker of poor outcomes for [all of] these reasons," she said.

Each Person With Diabetes Is Different; Use Common Sense

All of this makes it tricky to tease out diabetes' individual contribution to infection risk.

"The proportion in which each medical condition contributes to...risk of infection is hard to dissect out," explained Andrea Luk, MBChB, FHKCP, FHKAM.

Luk is an associate professor at the Chinese University of Hong Kong and is the other senior coauthor of the study in Diabetologia.

"Certainly a person with both diabetes and cardiovascular disease would have more risk than someone with diabetes and good glucose control and without any other comorbidities," she continued.

But because every person with diabetes is different, it is important to consider the whole package, she stressed.

Whether someone with diabetes succumbs to infection has a lot to do with glycemic control, diabetes duration, and diabetes-related comorbid conditions, such as heart disease, kidney disease, and stroke, as well as their age, weight, and whether they smoke.

Chan further clarified: "We have to judge this case by case. You cannot apply it across the board to all people with diabetes. A person with well-controlled diabetes is very different from someone with poorly controlled diabetes. They have a different set of risk factors and complications."

While awaiting more detailed analysis, Chan, Luk, and Malani all suggest common-sense measures for patients with diabetes, CVD, and other chronic conditions: staying up to date with vaccinations, avoiding large crowds, frequent hand washing, avoiding touching eyes or mouth (the so-called T-zone), and wearing face masks in areas where COVID-19 is prevalent.

People with symptoms should also wear a face mask to avoid spreading infection to others.

Also a Bad Year for Flu, Hard to Discern Between the Two

Malani added, "Although there is a lot of focus and concern about COVID-19, this has [also] been a terrible year for seasonable flu. I recommend flu shots, especially for...patients with diabetes."

She also suggested being thoughtful about travel.

"This may not be a good time for nonessential travel to Asia, as the situation there is evolving. COVID-19 risk is still low, depending on where you go, but the risk of disrupted travel is real," she noted.

Even without an emergency such as COVID-19, Chan and Luk say they cannot stress highly enough the importance of optimal glucose control for people with diabetes.

"People with diabetes or other chronic conditions should be extra vigilant about protecting themselves from infection," Luk reiterated.

They should also have a lower threshold for seeking care if they feel they are developing symptoms of infection, she noted.

"It's hard to tell at the beginning whether it's influenza or COVID-19 because they present similarly," she said.

Chan, Luk, and Malani have disclosed no relevant financial relationships.

For more diabetes and endocrinology news, follow us on Twitter and Facebook.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.