What HbA1c levels are considered diagnostic for prediabetes and diabetes mellitus (DM)?

Updated: Sep 27, 2021
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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An HbA1c below 6%is considered normal glucose tolerance (using an assay that has been standardized to the DCCT normal range of 4-6%). An HbA1C of 6-6.4% is neither normal glucose tolerance nor diabetes. With current assays, an HbA1c of less than 5.7% is considered normal and an HbA1c of greater than 6.4% is considered diagnostic for diabetes mellitus (DM). A value between 5.7% and 6.4% is considered diagnostic of prediabetes.

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