Clinical Use

  • Perform the A1C test at least two times a year in patients who are meeting treatment goals (and who have stable glycemic control).
  • Perform the A1C test quarterly in patients whose therapy has changed or who are not meeting glycemic goals.

From the Executive Summary of the 2014 American Diabetes Association Clinical Practice Recommendations (Diabetes Care 2014;37,suppl.1:S5-13)

  • Consider A1C targets as close to non-diabetic levels (< 6.5 percent) as possible without significant hypoglycemia in people with short duration of diabetes, little comorbidity, and long life expectancy.
  • Consider less stringent A1C targets (e.g., 8 percent) for people with a history of severe hypoglycemia, limited life expectancy, extensive comorbid conditions, advanced complications, major impairments to self-management (e.g., visual, cognitive, social), or long-standing diabetes where the A1C goal is difficult to attain despite optimal efforts.
  • Reassess A1C targets and change (lower or higher) as appropriate.

From: National Diabetes Education Program website on Guiding Principles,

When interpreting laboratory results health care providers should:

  • be informed about the A1C assay methods used by their laboratory
  • send blood samples for diagnosis to a laboratory that uses an NGSP-certified method for A1C analysis to ensure the results are standardized
  • consider the possibility of interference in the A1C test when a result is above 15% or is at odds with other diabetes test results
  • consider each patient’s profile, including risk factors and history, and individualize diagnosis and treatment decisions in discussion with the patient

From: National Diabetes Information Clearinghouse (NDIC),

NIDDK Diabetes & Prediabetes Tests Fact Sheet

Links to clinical guidelines from other organizations are listed below; the NGSP does not endorse specific guidelines.  

American Association of Clinical Endocrinologists’ (AACE) Comprehensive Diabetes Management Algorithm

ADA/American Geriatrics Society Consensus Report on Diabetes in Older Adults

ADA/Endocrine Society Consensus Report on Hypoglycemia

European Association for the Study of Diabetes (EASD)/ADA Position Statement on the Management of Hyperglycemia in Type 2 Diabetes

European Society of Cardiology (ESC)/EASD Guidelines on Diabetes, Pre-diabetes and Cardiovascular Diseases

International Diabetes Federation (IDF) Global Guideline for Type 2 Diabetes

IDF/International Society for Pediatric and Adolescent Diabetes (ISPAD) Guideline for Diabetes in Children and Adolescents

NDEP Guiding Principles for the Care of People With or at Risk for Diabetes

US Veteran’s Administration/Department of Defense Clinical Practice Guidelines

HbA1c Recommended for Diagnosis

The ADA Clinical Practice Recommendations now recommend using HbA1c to diagnose diabetes using a NGSP-certified method and a cutoff of HbA1c ≥6.5%. POC assay methods are not recommended for diagnosis.

A1C or "the A1C test"

The National Diabetes Education Program and major clinical diabetes organizations including the American Association of Clinical Endocrinologists, the American Society of Clinical Endocrinologists and the American Diabetes Association recommend use of the term A1C or "the A1C test" to describe HbA1c in clinical practice.