Researchers have revealed that people with diabetes and eye disease have a five-fold increased risk of requiring intubation when hospitalised with Covid-19.
The study, published in the journal Diabetes Research and Clinical Practice, identified for the first time the risk associated with diabetic retinopathy and Covid-19.
"This is the first time that retinopathy has been linked to severe Covid-19 in people with diabetes," said study author Antonella Corcillo from the King's College London in the UK.
"Retinopathy is a marker of damage to the blood vessels and our results suggest that such pre-existing damage to blood vessels may result in a more severe Covid-19 infection requiring intensive care treatment," Corcillo added.
The study investigated 187 people with diabetes (179 with type 2 diabetes and eight with type 1 diabetes) hospitalised with Covid-19.
Diabetic retinopathy was reported in 67 (36 per cent) of patients, the majority with background retinopathy.
Of the 187 patients hospitalised with severe Covid-19, 26 per cent were intubated and 45 per cent of these patients had retinopathy. Retinopathy was associated with a five-fold increased risk for intubation.
In the cohort, 32 per cent of patients died and no association was observed between retinopathy and mortality.
According to the researchers, there is increasing evidence that there is significant damage to the blood vessels in the lung and other organs in patients hospitalised with severe Covid-19.
People with diabetes are at high risk of vascular complications affecting the large and small blood vessels.
"We hypothesise that the presence of diabetes-related vascular disease such as retinopathy may result in greater vulnerability and susceptibility to respiratory failure in severe Covid-19," study author Janaka Karalliedde.
The researchers noted that further studies are required to investigate the possible mechanisms that explain the links between markers and manifestations of diabetic vascular disease such as retinopathy and severe Covid-19.