A national issue has been identified with some HbA1c blood test results that were carried out between 1 July and 22 November 2024.
This test is commonly used to help diagnose and monitor diabetes and pre-diabetes.
During this time, certain laboratory equipment used in some NHS labs may have given results that were slightly too high. This happened due to a problem with how the machines were calibrated (set to give accurate readings).
Several trusts across the country have been impacted, including South Tees Hospitals NHS Foundation Trust.
Any tests taken outside of the above dates are not affected.
This national issue was due to a problem with supply of calibrator material from the manufacturer which affected the analysers used for HbA1c blood tests.
The issue was resolved after 22 November 2024 by using a new calibrator. The trust also moved to a new testing provider in June 2025.
What you need to know…
- We are working closely with GP partners and clinical teams to identify any patients who may have been affected and determine the appropriate next steps.
- We are in the process of contacting all individuals whose results may have been impacted to offer further information and invite them for a follow-up review where needed.
- If you have not been contacted, please do not call your GP or the hospital. We are proactively reaching out to all patients who require follow-up and ask for your patience while we carry out this important work.
- This issue relates to HbA1c tests taken between 1 July and 22 November 2024 only.
- The issue was resolved after 22 November 2024, by using a new calibrator.
- The analysers involved were used exclusively for HbA1c testing, so no other blood tests have been affected.
- Patients should continue to attend any scheduled blood test appointments as normal.
We sincerely apologise for any distress or inconvenience this may have caused. A full review is underway to understand how this occurred.
Frequently asked questions (FAQs)
How do I know if I’ve been affected?
Your GP will review your test results. If action is needed, they will contact you directly. There is no need to call your GP unless you have been contacted.
What should I do if I’ve been told I have diabetes or prediabetes?
Do not stop any medication or treatment. If your result is under review, your GP will guide any changes based on a new test.
Are future HbA1c results safe?
Yes. Additional quality checks have been put in place, and no tests taken before 1 July 2024 or after 22 November 2024 have been affected. South Tees Hospitals NHS Foundation Trust also moved to a new HbA1c testing provider in June 2025.
Will this delay my care?
No. If further action is needed, your GP will contact you promptly to ensure appropriate care continues.
What should I do if I’ve already been referred to a diabetes programme (DESMOND, DAFNE)?
It is safe to continue. These programmes provide useful lifestyle support and do not cause harm if your diagnosis is later revised.
If this national issue occurred between July and November 2024 why are you only sharing this information now?
The trust was not made aware of the issue until April 2025. We have had to work through a lot of data to assess the scale of the problem and review thousands of patient records to ensure the correct people could be contacted with accurate information. We also had to ensure all local GPs were fully aware of the issue and that steps were in place to prevent the issue from reoccurring.
What if I have a concern or complaint?
If you have already been contacted by your GP and wish to raise a concern or a complaint, please contact: South Tees Hospitals NHS Foundation Trust patient experience team:
Email: [email protected]
Telephone: 01642 854807
Freephone: 0800 0282451