One in five diabetes patients who are hospitalised with the coronavirus die within 28 days, research suggests.
Statistics have repeatedly flagged people with certain underlying medical conditions are more likely to develop COVID-19, the disease caused by the infection.
When it comes to being vaccinated, adults aged 16 to 65 with diabetes in the UK fall into priority group six, with them being considered an "at-risk group".
These individuals are not deemed to be "extremely clinically vulnerable", however, unlike those with certain cancers or severe asthma.
To learn more, scientists from University Hospital Nantes analysed more than 2,700 diabetes patients who were hospitalised with the coronavirus across France.
Results reveal 577 (20%) died within 28 days of admission.
More than four in five (88%) of the patients had type 2 diabetes, which is often brought on by obesity. Carrying a dangerous amount of weight has long been recognised as a risk factor for coronavirus complications.
This comes after scientists from the University of Exeter reported a 40-year-old with diabetes has the same coronavirus death risk as a 60-year-old with the infection but not the medical condition.
"The identification of favourable variables associated with hospital discharge and deleterious variables associated with death can lead to patient reclassification, and help to use resources adequately according to individual patient profile," the scientists wrote in the journal Diabetologia.
In the UK, 3.9 million people have been diagnosed with diabetes, of whom around 90% have type 2. In the US, 34.2 million – 10.5% of the population – have diabetes, which is type 2 in 90% to 95% of cases.
In May, the Nantes scientists reported 10% of diabetes patients with the coronavirus die within seven days of hospital admission.
The ongoing study – called Coronado – has since enrolled more participants, of whom just under two-thirds (63%) were male.
On average, the patients were 69 and had an overweight body mass index.
As well as excess weight raising the risk of coronavirus complications, severe ill health is more common among men and older people with the infection.
Microvascular and macrovascular diabetes complications were found in 44% and 38% of the participants, respectively.
Microvascular complications specifically affect small blood vessels, often leading to damage to the kidneys, nerves or retina at the back of the eye. Macrovascular complications can trigger heart attacks and strokes.
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The results reveal half (50%) of the patients were discharged within 28 days of being admitted to hospital with coronavirus complications, most on day nine.
More than one in five, 577 patients, had died by this time.
Of the remaining participants, just over one in 10 (12%) were still hospitalised on day 28, while 17% had been transferred to another medical centre.
Being young and routinely taking the drug metformin were associated with a higher chance of discharge. Metformin lowers blood sugar levels in people with type 2 diabetes, usually when diet and exercise alone are insufficient to regulate insulin.
Perhaps surprisingly, a longer duration of symptoms upon admission was also linked to greater hopes of being sent home.
Deaths were higher among those with a history of microvascular complications.
Taking blood-thinning drugs was also linked to a higher fatality risk. Previous research suggests the coronavirus can make blood stickier, leading to strokes and even gangrenous limbs in severe cases.
Shortness of breath upon admission, abnormal liver enzyme levels, and higher immune cell and inflammatory marker counts were also associated with an elevated death risk.
Patients whose diabetes was regularly treated with insulin were found to be 44% more likely to die. People with type 1 diabetes do not produce insulin and therefore have to take the blood-sugar lowering hormone.
In type 2 diabetes – which occurs when the body does not produce a sufficient amount of insulin or respond to the hormone that is made – insulin is generally given when other medications no longer work.
The study's patients who took insulin may therefore have had more advanced diabetes.
None of the results were differentiated according to whether the patient had type 1 or 2 diabetes. Type 1 diabetes' onset is unrelated to a patient's diet or lifestyle.
Overall, taking statins for high cholesterol was linked to a 42% increased risk of death.
The scientists stressed their study was observational and therefore does not prove cause and effect.
It is difficult to draw any definite conclusions about how a diabetes patient's medication may influence their coronavirus death risk, they added.
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