An NHS trust has revealed that about 11,000 people will have to be re-tested after a hospital machine issued incorrect diabetes results.

The Bedfordshire NHS Foundation Trust said some patients may have been wrongly given higher blood glucose readings from a laboratory at the Luton and Dunstable Hospital.

A message on the trust website, external suggested patients could have been misdiagnosed with the condition as a result.

The trust has apologised “for any emotional distress and inconvenience”.

The trust said there had been an “intermittent issue” with a machine that analyses blood, with tests taken on certain dates in April and July.

The problem related to some HbA1C tests analysed at the hospital’s laboratory, and patients from across Luton, south Bedfordshire and Hertfordshire would be contacted, it said.

The procedure is known as the hemoglobin A1C test (HbA1c) which measures average blood sugar levels.

Diabetes UK said it is used to diagnose and monitor, external the condition.

For people at risk of developing type 2 diabetes, their target HbA1c level should be below 42mmol/mol (6%), according to the charity.

John Hagen, 70, a retired photographer from Kensworth in Bedfordshire, was one of the people who received a letter from the trust asking him to get re-tested.

Already a diabetes patient, Mr Hagen’s GP increased his medication after results came back which were “through the roof”.

“I then got a letter saying the results were a false positive,” he said.

“My GP will be re-running the test but we have agreed not to amend my medication downwards.

“I worry about things when there’s something to worry about. I acknowledge that mistakes happen and in a pressurised environment like the NHS it can sometimes take a while to realise something is wrong,” Mr Hagen added.

On its website, the trust said: “You may receive a call from the hospital in the coming weeks asking you to come and have another blood sample taken for re-testing.

“Please be assured that we will contact you if your result might have been affected.

“We are asking residents to please avoid calling the hospital or your GP to ask whether you need to be re-tested because we need to focus our effort on arranging the re-tests with those patients who need them”.