The WHO criteria regarding label disordered blood glucose metabolism diabetes mellitus, impaired glucose tolerance or impaired fasting glucose.
A. Diabetes Mellitus:
I. Symptomatic Patient:
If any of the following readings is present in a symptomatic patient then that patient can be diagnosed with diabetes mellitus.
1. Fasting blood glucose level of equal to or more than 7.0 mmol/l is diagnostic of diabetes mellitus in symptomatic patients.
2. Random blood glucose level or glucose level measured 2 hours after 75 grams of glucose ingestion (oral glucose tolerance test) equal to or more than 11.1 mmol/l is diagnostic of diabetes mellitus in symptomatic patients.
II. Asymptomatic Patients:
Criteria for diagnosis of diabetes mellitus among asymptomatic patients are same as those for symptomatic patients however these should be demonstrated at two separate occasions to be diagnostic of diabetes mellitus among asymptomatic patients.
III. Use of HbA1c for The Diagnosis of Diabetes Mellitus:
1. An HbA1c level of equal to or more than 6.5% (48mmol/mol) is diagnostic of diabetes mellitus on symptomatic patients.
2. Among asymptomatic patients, above value should be demonstrated at least twice on separate occasions.
3. An HbA1c value of less than 6.5% does not exclude diabetes mellitus.
4. It should also be kept in mind that conditions causing increased red cell turn over such as anemia, hemoglobinopathies, pregnancy etc. can give misleading HbA1c values.