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A1C
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Diabetes Mellitus

A1C

The A1C test is a diagnostic tool that measures your average blood glucose levels over the past three months to help identify and manage diabetes.

Overview

The A1C is a blood test used for type 2 diabetes and prediabetes. It measures your average blood glucose, or blood sugar, level over the past 3 months. Doctors may use the A1C alone or in combination with other diabetes tests to make a diagnosis. They also use the A1C to see how well you are managing your diabetes. This test is different from the blood sugar checks that people with diabetes do every day.

Understanding Your Results

Your A1C test result is given in percentages. The higher the percentage, the higher your blood sugar levels have been:

  • Normal: An A1C level below 5.7%.
  • Prediabetes: A level between 5.7% to 6.4%. Having prediabetes is a risk factor for getting type 2 diabetes, and individuals may need retests every year.
  • Type 2 Diabetes: A level above 6.5%.

Management and Goals

If you have diabetes, you should have the A1C test at least twice a year. The A1C goal for many people with diabetes is below 7, though this may be different for you. You should ask your doctor what your specific goal should be. If your A1C result is too high, you may need to change your diabetes care plan.

Frequently Asked Questions

No, fasting is not required for an A1C test. Because the test measures the percentage of hemoglobin bound to glucose over the typical 90- to 120-day lifespan of red blood cells, acute dietary intake, short-term fasting, or recent meals do not alter the results.
Physicians often individualize A1C goals to 7.5% or 8.0% for individuals with a history of severe hypoglycemia, hypoglycemia unawareness, limited life expectancy, advanced cardiovascular disease, or extensive microvascular complications. In these populations, the acute dangers of low blood sugar outweigh the long-term benefits of intensive glycemic control.
Yes, conditions affecting red blood cell turnover can skew A1C readings. Falsely low results often occur in hemolytic anemia, acute blood loss, recent blood transfusions, or chronic kidney disease treated with erythropoietin. Falsely elevated results can occur in iron-deficiency anemia, vitamin B12 deficiency, or severe hyperbilirubinemia. Certain hemoglobin variants, such as sickle cell trait, can also cause inaccurate readings depending on the laboratory assay used.
Fingerstick tests capture a single snapshot in time, and continuous glucose monitors provide real-time glycemic variability, whereas A1C reflects a weighted average heavily influenced by blood sugar levels over the preceding 30 days. Discrepancies can also arise from significant glucose swings—where frequent severe highs and lows average out to a deceptively normal A1C—or variations in an individual's unique red blood cell lifespan.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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