https://www.scientificamerican.com/article/how-blood-sugar-can-trigger-a-deadly-immune-response-in-the-flu-and-possibly-covid-19/

Many of the people dying in the novel coronavirus pandemic appear to be harmed more by their own immune system than by the virus itself. The infection can trigger a cytokine storm—a surge in cell-signaling proteins that prompt inflammation—that hits the lungs, attacking tissues and potentially resulting in organ failure and death. But this phenomenon is not unique to COVID-19; it sometimes occurs in severe influenza, too. Now a study sheds light on one of the metabolic mechanisms that help orchestrate such runaway inflammation.

Scientists have long known that viral infections can affect human cellular metabolism, the system of biochemical reactions needed to provide energy for everything cells do. In the new paper, researchers showed that in live mice and human cells, infection with an influenza A virus—one of two types that typically cause seasonal flu—sets off a chain of cellular events, or a pathway, that boosts the metabolism of glucose. This action, in turn, triggers the production of an avalanche of cytokines. And blocking a key enzyme involved in the glucose pathway could be one way to prevent a deadly cytokine storm, according to the study, which was published last week in Science Advances.