What diabetics should know about the deadly 'black fungus' infections affecting India's COVID-19 patients

• Hospitals in India have seen a rise in cases of mucormycosis, or "black fungus," a life-threatening infection.
• Most of the patients affected are people with diabetes who previously had COVID-19.
• Diabetes, COVID-19, and steroids, which are sometimes used to treat COVID-19, all dampen the immune system, elevating a person's risk of "black fungus."

As India grapples with record-setting rates of COVID-19 cases, doctors are now facing an uptick in cases of another deadly infection, known as "black fungus."

The infection, technically called mucormycosis, appears to be mostly affecting diabetics who have recovered from COVID-19.

Mucormycosis is a rare but serious fungal infection in the sinuses and lungs. It can lead to black patches on the nose, blurred or double vision, and one-sided facial swelling, according to the Centers for Disease Control and Prevention. It's acquired through contact with fungal spores found in soil, plants, and manure.

Endocrinologists told Insider that, while black fungus is not new, the pandemic appears to have created the perfect storm.

People with diabetes have slightly dampened immune systems, meaning they already have an elevated risk of contracting black fungus. COVID-19, which worse-affects people with diabetes, increases that risk even more. And then there are steroids, a medicine sometimes used to treat critically ill COVID-19 patients, that can dampen the immune system.

While there have not been as many cases reported in other countries, Dr. Deena Adimoolam, a specialist in endocrinology and disease prevention, said all people with diabetes should be taking precautions to protect themselves from infections right now.

Black fungus rates around the world

Black fungus has historically been extremely rare, affecting 900,000 people per year, which is less than 1% of the population, in India a year, according to a study published in 2017. The same study found that only 10,000 people outside of India are affected each year.

The US does not have any national surveillance system in place for black fungus: the CDC's rates are based on a study in 1998, finding that there are 1.7 cases per one million people.

Why steroids and COVID-19 increase the risk of black fungus for people with diabetes

People with diabetes, in general, are slightly immunocompromised, because elevated blood sugar impairs the immune system. If diabetics "get an infection, then these patients are more likely to have trouble to fight off the infection," Dr. Rasa Kazlauskaite, an endocrinologist at Rush University Medical Center.

Diabetics have high blood sugar levels, too, which is an environment fungus thrives on. "Sugar feeds the fungus and then the fungus is stronger than immune system that is trying to fight it off," Kazlauskaite said.

What's more, steroids, which some evidence has shown has been found to help critically ill COVID-19 patients, may also reduce the immune system's ability to fight off infections because it suppresses the body's immune system.

The risk is particularly high in India

India has the second-highest diabetic population in the world, according to the International Diabetes Foundation's atlas, which amounts to 70.2 million people.

Adimoolam said people with diabetes in India are more vulnerable to infection because there may be a genetic risk in this population.

"Those in India who have diabetes tend to have a higher risk for developing complications of diabetes like kidney disease or wound infections," Adimoolam said.

Adimoolam also said mucor, the fungus linked to mucormycosis, can live on contaminated medical supplies, and that may be driving higher case counts in India.

Don't forgo steroid treatment if you're critically ill with COVID-19

Dr. Yogish Kudva, an endocrinologist at the Mayo Clinic, said if you have diabetes, try to prevent getting COVID-19.

"The key issue here is to be concerned about covid," Kudva said. He suggests following COVID-19 rules, like wearing a mask in a crowded area, and getting vaccinated.

For people with diabetes that have COVID-19 outside of India, Adimoolam said to make sure your blood sugar levels are within a normal range and continue to take prescribed medications. But if you're blood sugar levels high, contact your doctor.

If you're a diabetic hospitalized with COVID-19, Adimoolam said let your medical team know that you're diabetic, and "make sure you or your loved ones is advocated for good blood sugar control."

Above all else, Adimoolam said don't deny steroids if they're a lifesaving treatment.

"Even with high doses of steroids, high blood sugars can be controlled with certain medications."

Kazlauskaite also said diabetics hospitalized with COVID-19 should not refuse steroids.