Why Covid-19 Kills Those with Diabetes 

People with diabetes and Covid-19 have a greater chance of developing severe viral illness and dying at five times the risk of those without diabetes. 

At the end of March, preliminary data from the Centers for Disease Control and Prevention for about 7100 US coronavirus patients showed that, along with older age, various health conditions – most commonly diabetes, chronic lung disease, and heart disease – put patients at risk of developing a severe viral illness. Specifically, among intensive care patients with Covid-19, 32% had diabetes. For hospitalized Covid-19 patients not in the ICU, 24% had diabetes. Yet for people with Covid-19 who did not require hospitalization, only 6% had diabetes. 

Earlier, more extensive research from China published in JAMA showed a 2% fatality rate among Covid-19 patients. But this rate jumped to about 10% for those who also had cardiovascular disease and to about 7% among those with diabetes. A report from Italy found among 481 patients who died of the virus; about one-third had diabetes. That represents a risk of death five times higher than would be expected based on diabetes’ overall prevalence in Italy. While there’s much to learn about Covid-19, its course in people with diabetes appears to parallel that of influenza loosely. Outcomes are less stable, ventilators are more commonly needed, and severe complications are more likely in people with diabetes who get the flu. But the flu is not as dangerous as Covid-19 infection. And in Covid-19 patients with diabetes, additional risk factors such as heart disease, sometimes undiagnosed, are compounding the problem, 

The reasons are complicated. In people with type 2 diabetes, insulin resistance gives rise to chronic, low-grade inflammation, leaving the immune system dulled by this ongoing state of alert. New infections are like “crying wolf” – the immune system does not rally quickly and adequately, therefore allowing the virus to gain and maintain a foothold. We know that when the blood sugar is out of control, it reduces the ability for the body to fight off infections as it decreases our immune system and makes us more susceptible to just about every disease known to man, even those we don’t even know much about.  Reducing patients’ A1c into the normal ranges can make a significant difference in the ability to fight off any virus. 

Doctors’ experience with bacterial infections indicates that controlling blood sugar before and during infection can be helpful. During the crisis, it is advised that hospitalized Covid-19 patients who have diabetes ensure their glucose is carefully managed – and to monitor it themselves, with their own supplies, if they are able. 

A diabetes complication called diabetic ketoacidosis, or DKA, is a risk with other viral infections and a concern in coronavirus patients. DKA occurs when an absolute or relative insulin deficiency prevents cells from using glucose for energy, and they burn fat instead, creating chemicals called ketones that build up in the blood and can be toxic. Amid serious infections, certain diabetes drugs should be discontinued. Diabetes drugs called SGLT2 inhibitors contribute to an increased risk for DKA. Another diabetes drug, metformin, also might need to be discontinued in hospitalized coronavirus patients. Under extreme circumstances, including dehydration and kidney disease, metformin could foster acidosis and even exacerbate kidney disease when intravenous contrast agents are used in imaging. Patients with Covid-19 should talk to their doctor about stopping these medications at the time of hospitalization, and possibly sooner. 

Practice Pearls: 

• Outside the hospital, the ADA recommends keeping blood sugar well–controlled and consulting health care professionals about managing risk and any viral symptoms. 
• If feeling very ill – including higher fever with cough and shortness of breath – people should seek emergency care. 
• Patients with diabetes need to be alert about not delaying medical help if they’re getting sick, particularly over a short time interval. 

Diabetes Care 2020 May; 43 (5): 1165. https://doi.org/10.2337/DC20-ie05 

Stephen Freed, R.Ph., Diabetes Educator, Publisher