South Asian people are at highest risk of dying from Covid-19 after being admitted to UK hospitals, even when factors such as obesity are taken into account, the biggest study of its kind has found.

Data from 30,693 people admitted to 260 hospitals found a 19% increased risk of death with coronavirus for those who were South Asian compared with white people.

Experts behind the study said 40% of the South Asians in the group had diabetes – which was a “significant factor” in their increased risk of death.

40% of the South Asians in hospital with Covid-19 have diabetes; we think this is quite a significant contributor to their increased likelihood of death

Professor Ewen Harrison, from the University of Edinburgh, who led the study, told the PA news agency that the increased risk of death was not due to obesity, which is linked to many cases of Type 2 diabetes.

“South Asian people, in fact, on average, have a lower weight compared with the white group,” he said.

He said that, of the increased risk of death between South Asians and whites, a fifth may be explained by diabetes.

The paper showed that, overall, those who were South Asian were a fifth more likely to die with coronavirus, while those who were black appeared no more likely to die, and other ethnic minorities had no higher risk compared with white people.

Prof Harrison said: “What our study is asking is, once you’re in hospital, are you more at risk if you’re in a particular ethnic group?

“There may be many more black people in hospital as a proportion of the population and therefore many more may be dying (as a proportion of the overall population).

“But once they get to hospital, we don’t see a strong signal that they (black people) have a worse outcome, and you didn’t find that for other ethnic minorities either.”

He said there may be a biological effect for South Asian risk, “meaning there may be something in your genes which makes you more likely to either get the disease, to get a severe form or to die from the disease”, though this needs further exploration.

He said the paper has policy implications around workplace risk assessment, easing of lockdown and the provision of personal protective equipment (PPE) for frontline workers.

It may also change who is eligible for any vaccine that is developed in the fight against Covid-19.

The South Asian group in the paper included people with Indian, Pakistani and Bangladeshi heritage but not those from East Asia and Southeast Asia.

The data for the research was taken from hospitals in England, Scotland and Wales from February 6 to May 8, with patient follow-up to May 22.

The study, which has not yet been peer-reviewed or published in a medical journal, included 1,388 people of South Asian background (5% of the total group), 266 who were East Asian (1%), 1,094 who were black (4%), 2,398 who were other ethnic minority (8%) and 25,547 who were white (83%).

Ethnic minorities were younger and more likely to have diabetes (Type 1 and Type 2) but had fewer other underlying health conditions such as chronic heart disease or dementia than people who were white.

No difference was seen between ethnic groups when it came to the severity of illness on admission to hospital.

People who were South Asian were 28% more likely to be admitted to critical care, as were those who were black (36% increased risk), compared with those who were white, the study found.

This held true even when age, sex and place of admission were taken into account, and the impact of deprivation.

The team concluded: “Ethnic minorities in hospital with Covid-19 were more likely to be admitted to critical care and receive IMV (ventilation) than whites, despite similar disease severity on admission, similar duration of symptoms, and being younger with fewer comorbidities.

“South Asians are at greater risk of dying, due at least in part to a higher prevalence of pre-existing diabetes.”

Prof Harrison told BBC Radio 4’s Today programme: “South Asian people look very different in hospital to other groups, in particular, white people.

“They’re younger, 12 years younger in average (with an average of 60), less likely to have pre-existing conditions such as lung disease, dementia or obesity but much more likely to have diabetes.

“In fact 40% of the South Asians in hospital with Covid-19 have diabetes, we think this is quite a significant contributor to their increased likelihood of death.”

Professor Calum Semple, from the University of Liverpool, who also worked on the study, said he believed people from South Asia had an increased exposure risk to Covid-19 via their jobs, such as working in health and social care.

NHS Blood and Transplant (NHSBT) has discovered that people from Asian communities who have recovered from Covid-19 are more likely to have the antibody-rich convalescent plasma which can save lives.

It is calling for new donors as it collects convalescent plasma for a major new coronavirus treatment trial.

The plasma can be transfused into people who are struggling to develop their own immune response.