The Cumberland Health Authority and the Pictou County Health Authority issued a joint statement saying they are contacting patients and their health-care providers to recommend followup and possible retesting.
The A1c lab tests produced by Siemens Healthcare Diagnostics are used to track blood sugar levels.
The company says they may have produced results that were higher than expected.
The tests were done in the Pictou area between December 2013 and May 2014, and between January and June of this year in the Cumberland region.
Bruce Quigley, CEO of the Cumberland Health Authority, says it's not possible to determine if any individual test was wrong.
"We understand that this type of positive bias may have resulted in a health-care provider being more cautious than otherwise would have been the case, not less so," he said in a statement Monday.
"Accordingly, we encourage patients to follow up with their provider to determine if additional testing is required."