The Pros and Cons of Diagnosing Diabetes With A1C

  1. Jaakko Tuomilehto, MD, MA, PHD2
  1. 1Division of Endocrinology and Metabolism, Department of Medicine, University and University Hospital of Verona, Verona, Italy
  2. 2Department of Public Health, University of Helsinki, Helsinki, Finland; South Ostrobothnia Central Hospital, Seinajoki, Finland; and Red RECAVA Grupo RD06/0014/0015, Hospital Universitario La Paz, Madrid, Spain
  1. Corresponding authors: Enzo Bonora, enzo.bonora{at}, and Jaakko Tuomilehto, tuomileh{at}

An International Expert Committee was convened in 2008 by the American Diabetes Association (ADA), the European Association for the Study of Diabetes, and the International Diabetes Federation to consider the means for diagnosing diabetes in nonpregnant individuals, with particular focus on the possibility to indicate A1C as an alternative if not a better tool (1). After reviewing the available literature and a thorough discussion on the advantages and the limits of previous diagnostic strategies (essentially based on fasting glucose assessment) and the considered alternative approach (based on A1C measurement), a consensus was reached that the latter (i.e., A1C) should be included among diagnostic tools for diabetes and, with the exception of a number of clinical conditions, should even be preferred in diabetes diagnosis in nonpregnant adults.

The main conclusion of the International Expert Committee was implemented in the most recent clinical recommendations issued by the ADA. However, in these guidelines, A1C is indicated as a diagnostic tool alternative but not superior to blood glucose, leaving to the health care professional the decision about what test to use in an individual.

The World Health Organization is currently examining the proposal made by the International Expert Committee and is carefully addressing the controversial issues still remaining, most of which have been the subject of letters to the editor and articles recently published in the literature. Nevertheless, the use of A1C for diagnosing diabetes is rapidly becoming a reality in many Western countries.

In the text that follows, one of us (E.B.) will present the main points supporting A1C (pros) and the other (J.T.) will illustrate the main counterpoints challenging A1C (cons) as the primary tool for diabetes diagnosis. The text has been prepared in full coordination and the final conclusions represent the opinion of both authors. Tables 1 and 2 summarize the …

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