Study links long Covid to dangerous chronic disease cycle

A study by ERR reports that long Covid and chronic illnesses are linked in a direct two-way relationship. Existing conditions can prolong Covid symptoms, while prolonged illness may contribute to new diagnoses, including sleep apnoea and cardiac arrhythmias.

Researchers at the University of Tartu analysed health and genetic data from nearly 210,000 donors to the Estonian Biobank. They compared the medical histories of more than 2,000 people with long Covid with those of approximately 200,000 people in a control group.

People aged 40 to 59 were most likely to develop long Covid, and women accounted for three-quarters of those with persistent symptoms. Being overweight, having chronic kidney disease, asthma or type 2 diabetes also significantly increased the risk. For people with chronic obstructive pulmonary disease, the risk of symptoms persisting was more than twice as high as usual.

The relationship also worked in the opposite direction. During the pandemic years, doctors diagnosed new health problems significantly more often in patients with long Covid. Their risk of sleep apnoea, or breathing interruptions during sleep, was three times higher than before. Cardiac arrhythmias and thyroid diseases also became more common.

The researchers said they could not completely rule out the possibility that people with long Covid visited doctors more frequently and therefore received more diagnoses.

The study also examined type 2 diabetes. From spring 2020, the number of new diabetes cases across the population rose sharply, exceeding all previous mathematical forecasts. Heredity also played a clear role: people with a stronger genetic predisposition to severe Covid-19 developed diabetes 17 percent more often.

According to the researchers, the virus can damage the body in several ways. Existing chronic illnesses may create conditions that promote inflammation and immune system disorders, preventing the body from fully recovering from the infection. The virus may also affect the pancreas, which produces insulin to regulate blood sugar.

Pandemic-era lifestyle changes further contributed to the development of new illnesses, the researchers said. People moved less, stress increased and body weight rose.

The researchers published their findings in the journal Frontiers in Public Health.