Covid-19 may trigger high sugar levels, worsen disease

New York

Covid-19 infection triggers hyperglycemia, or high bloodsugar levels, by disrupting key fat cells, bringing high risks of severedisease and death in many patients, according to a new study.

Hyperglycemia, the core feature of diabetes, is associated with inflammationand weakened immunity against infections, and was recognised as a significantrisk factor for severe Covid-19 early in the pandemic.

However, doctors later began finding evidence that Covid-19 is associated withhyperglycemia in patients who have no history of diabetes.

In the study, reported in the journal Cell Metabolism, the researchers foundthat the deadly infection induces hyperglycemia by disrupting fat cellsa�production of adiponectin -- a hormone produced by fat cells which normally hasa protective effect against diabetes by enhancing insulin sensitivity.

"We normally don't think that fat cells are very active, but in fact theysynthesise many protective proteins for your body -- and it appears thatSARS-CoV-2 may disable that protection in many patients," said James Lo,Associate Professor of medicine and cardiologist at the NewYork-Presbyterian/Weill Cornell Medical Centre.

For the study, the team analysed the records of 3,854 patients who werehospitalised with Covid-19 in the first few months of the pandemic in the US.

They found that a remarkably high proportion (49.7 per cent) of these patientspresented with hyperglycemia or developed it during their hospital stays.

Compared to patients with normal blood sugar levels, the patients withhyperglycemia were nine times more likely to develop severe lung dysfunction(acute respiratory distress syndrome, or ARDS), 15 times more likely to begiven mechanical ventilation, and three times more likely to die.

Further tests also revealed that the Covid-19 ARDS patients had severe declinesin blood levels of adiponectin.

Hyperglycemia also occurs in patients with severe influenza or bacterialpneumonia, majorly by the death or dysfunction of beta cells that produceinsulin, which is the principal hormone that regulates blood sugar levels.

"In contrast, hyperglycemia in Covid-19 patients is mainly caused byinsulin resistance, in which insulin is present but the tissues it normallyacts upon are no longer sensitive to it," said first author MoritzReiterer, a postdoctoral fellow at the Centre.

"Patients with obesity, for example, may be more vulnerable to Covid-19because they may already have some degree of insulin resistance and fat celldysfunction, and possibly their fat cells are more susceptible toinfection," added Lo.