Is HbA1c the gold standard for diagnosis of Diabetes?

HbA1c is not a sure-fire tool for Diabetes diagnosis.At the European Association for the Study of Diabetes meeting on HbA1c for diagnosis, many physicians did not trust glycated hemoglobin levels alone to diagnose diabetes, despite ADA guidelines. High-risk, pre-diabetic patients could be left untreated with an HbA1c of less than 6.5%, and a fasting Glucose or a Glucose tolerance test is often indicated to confirm a diagnosis. Several of the studies presented at the EASD meeting suggested that many patients in high-risk populations who indeed had diabetes were missed by the 6.5% cutoff.
In January 2010, the ADA advocated use of an HbA1c greater than or equal to 6.5% to diagnose diabetes. Historically, the test has been recommended only for monitoring glucose control, while diagnosis was dependent on tests of fasting plasma glucose (126 mg/dL or 7.0 mmol/L) or the two-hour glucose tolerance test (200 mg/dL or 11.1 mmol/L).
Advantages of HbA1c over blood sugars include that fasting is not necessary and that HbA1c is not affected by stress and thus more reliable. Glycated hemoglobin is also generally higher for certain ethnic groups, particularly blacks, as well as older patients and is affected by anemia, which may lead to misdiagnosis.
Most physicians in the audience during a lecture presentation preferred blood sugars over HbA1c.
(reported in Medpage, September 30, 2010)