hemoglobin A1c

noun

: a stable glycoprotein formed when glucose binds to hemoglobin A in the blood

Blood sugar was assessed by measuring the amount of hemoglobin A1c in the participants' blood, a test that looks for hemoglobin with sugar attached to it.

—Gina Kolata

also : a test that measures the level of hemoglobin A1c in the blood as a means of determining the average blood sugar concentrations for the preceding two to three months

Note: Both the glycoprotein and the test are also called A1c, glycated hemoglobin, glycohemoglobin, glycosylated hemoglobin, HA1c, and HbA1c.

Examples of hemoglobin A1c in a Sentence

Recent Examples on the Web

Orforglipron met the trial’s other goals of reducing patients’ hemoglobin A1c, a measure of blood sugar levels. —Joshua P. Cohen, Forbes.com, 2 Sep. 2025

The group with probiotics had greater decreases in hemoglobin A1c (HbA1c) and fasting blood glucose (FBG). —Jessica Swirble, Verywell Health, 5 Aug. 2025

Both have advised her to let her hemoglobin A1c, a measure of average blood glucose over several months, rise past 7%. —The New York Times, San Diego Union-Tribune, 15 Apr. 2025

That accounts for a number of routine lab tests, including a comprehensive metabolic panel, lipid panel, CBC with differential, hemoglobin A1c and thyroid-stimulating hormone. —John Yoo and John Shu, Newsweek, 23 Jan. 2025

Word History

First Known Use

1964, in the meaning defined above

Medical Definition

hemoglobin A1c

noun

-ˌā-ˌwən-ˈsē

: a stable glycoprotein formed when glucose binds to hemoglobin A in the blood

Blood sugar was assessed by measuring the amount of hemoglobin A1c in the participants' blood, a test that looks for hemoglobin with sugar attached to it.

—Gina Kolata

also : a test that measures the level of hemoglobin A1c in the blood as a means of determining the average blood sugar concentrations for the preceding two to three months

called also A1c, glycated hemoglobin, glycohemoglobin, glycosylated hemoglobin, HA1c, HbA1c