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.