The HbA1c standards are fairly universal and suggested by the World Health Organisation
In the UK these are the HbA1c levels for diagnosing diabetes are:
Below 6% (42) is normal
6% to 6.4% (42 to 47) is pre-diabetic
6.5% (48) or over is diabetic.
However, this is only for diagnosis. Once a person has been diagnosed there are different acceptable targets, which is why you may be seeing different numbers. These targets are higher than the ones used for diagnosis, and also vary according to whether you are on insulin or not. Insulin users have higher targets, as do older people. They are not set by the lab. They are agreed between the doctor and the patient.