Objective: Diabetes is under-diagnosed. About one-third of people with diabetes do not know they have it, and the average lag between onset and diagnosis is 7 years. This report reconsiders the criteria for diagnosing diabetes, and recommends screening criteria, in order to make case-finding easier for clinicians and patients.

Participants: One of the authors invited experts in the area of diagnosis, monitoring and management of diabetes to form a panel to review the literature and develop consensus regarding the screening and diagnosis of diabetes with particular reference to the use of hemoglobin A1c (HbA1c). Participants met in open session and by e-mail thereafter.

Evidence: Literature search was performed using standard search engines.

Consensus Process: The panel heard each member's discussion of the issues, reviewing evidence prior to drafting conclusions. Principal conclusions were agreed upon, and then specific cut-points were discussed in an iterative consensus process.

Conclusions: The main factors in support of using HbA1c as a screening and diagnostic test include: a) HbA1c does not require patients to be fasting; b) HbA1c reflects longer-term glycemia than does plasma glucose; c) HbA1c laboratory methods are now well standardized and reliable; d) errors caused by non-glycemic factors affecting HbA1c such as hemoglobinopathies are infrequent and can be minimized by confirming the diagnosis of diabetes with a plasma glucose (PG)-specific test. Specific recommendations: 1) Screening standards should be established that prompt further testing and closer follow-up, including fasting PG 100 mg/dl, random PG 130 mg/dl or HbA1c > 6.0%; 2) HbA1c 6.5 - 6.9%, confirmed by a PG-specific test (FPG or OGTT), should establish the diagnosis of diabetes; 3) HbA1c 7%, confirmed by another HbA1c or a PG-specific test (FPG or OGTT) should establish the diagnosis of diabetes.

The recommendations are offered for consideration of the clinical community and interested associations and societies.(Ref: Saudek CD et al.J Clin Endocrinol Metab. 2008 Jul;93(7):2447-53).