What are the recommended diagnostic thresholds for diabetes using fasting plasma glucose, random plasma glucose, and HbA1c?

The WHO-based thresholds are: fasting plasma glucose 7.0 mmol/L or higher, random plasma glucose 11.1 mmol/L or higher, and HbA1c 48 mmol/mol (6.5%) or higher. If the person has classic symptoms, one abnormal result is enough; without symptoms, the abnormal result must be confirmed on a second occasion.

For diagnosis, a fasting plasma glucose of 7.0 mmol/L or greater, a random plasma glucose of 11.1 mmol/L or greater, or an HbA1c of 48 mmol/mol (6.5%) or greater indicates diabetes. When symptoms such as polyuria, thirst, or unexplained weight loss are present, a single abnormal result is sufficient. In the absence of symptoms, two abnormal results are required, ideally using the same test. If HbA1c is used without symptoms, it should be repeated immediately to confirm; alternatively, an HbA1c of 48 mmol/mol or more can be combined with a single elevated plasma glucose (fasting 7.0 mmol/L or random 11.1 mmol/L) to make the diagnosis. HbA1c should not be used for diagnosis in children and young people, suspected type 1 diabetes, acute illness, pregnancy, end-stage renal disease, certain HIV treatments, or conditions affecting red blood cell lifespan.