A type of drug used for the treatment of type 2 diabetes and obesity has been linked to a reduced risk of hospitalisation, respiratory complications, and death in people with COVID-19 who have type 2 diabetes.

Researchers have said that glucagon-like peptide-1 receptor (GLP-1R) agonists appear to be “highly protective” but have cautioned that further studies are required to establish the link.

The team, from Penn State College of Medicine in America, examined the medical records of almost 30,000 people with COVID-19 between January and September 2020, who also have type 2 diabetes.

They found that those taking GLP-1R agonists in the six months before their COVID-19 diagnosis were much less likely to suffer severe complications from the disease in comparison to those of a similar age, race, ethnicity, sex, body mass index and pre-existing conditions.

Professor Patricia Grigson, chair of the Department of Neural and Behavioral Sciences, said: “Our results are very promising as GLP-1R agonist treatment appears to be highly protective, but more research is needed to establish a causal relationship between the use of these drugs and decreased risk for severe COVID-19 outcomes in patients with type 2 diabetes.”

People with diabetes are at a greater risk of severe COVID-19 outcomes, with a recent study highlighting that almost a third of COVID-19-related deaths in England were made up of people with type 2 diabetes.

The Penn State researchers predicted that GLP-1R agonists could offer some protection from severe COVID-19 outcomes due to their anti-inflammatory properties. Swelling of body tissues is often experienced by people with type 2 diabetes, while overactive inflammatory responses have been found in severe COVID-19 cases and deaths.

As part of their study, researchers also looked at dipeptidyl peptidase-4 (DPP-4) inhibitors and pioglitazone, two other drugs used to treat type 2 diabetes. The DPP-4 inhibitors demonstrated a lesser risk of respiratory complications, while pioglitazone was associated with a reduced risk of hospitalisation. However, neither demonstrated a reduction in the risk of death from COVID-19 or the strong trends shown by GLP-1R agonists in reducing COVID-19 complications across the board.

Dr Nazia Raja-Khan, associate professor of medicine and endocrinologist at Penn State Health Milton S. Hershey Medical Center, said: “Further research is needed to confirm whether GLP-1R agonists can protect against severe COVID-19 complications. There is also a need to determine the conditions in which these drugs could be protective and how they could be used safely during COVID-19 hospitalisation.”

The study has been published in the journal Diabetes.