Hemoglobin A1c
DESCRIPTION
- Hemoglobin A1C (HbA1c) is a stable adduct of glucose on the beta-chain of hemoglobin (N-[1-deoxyfructosyl]hemoglobin).
- Formed by a largely irreversible reaction, post-translationally and non-enzymatically, when hemoglobin circulating in a red blood cell is exposed to ambient glucose
- Alternate terms: "A1C" (preferred for use in communication with patients), "glycated hemoglobin" (the most accurate term), glycosylated hemoglobin.
- Expressed most often as the percent of hemoglobin that is glycated (alternatively, as mmol glycated hemoglobin per mole total hemoglobin).
- The single best test to monitor overall blood glucose control in diabetes[6]
- Reflects the average blood glucose over about 3 months previously, although somewhat disproportionately weighted to recent blood glucose levels[12]
- A strong indicator of risk for long-term diabetic complications, especially retinopathy, neuropathy and nephropathy (DCCT).
- Also an indicator of cardiovascular disease (CVD) risk, although glucose control is less strong of a risk factor for CVD than lipids, blood pressure and smoking[8]
- HbA1c > 6.5% is one criterion for diagnosing diabetes[2][3].
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Last updated: July 7, 2020
Citation
Sarkar, Sudipa, and Thomas Donner. "Hemoglobin A1c." Johns Hopkins Diabetes Guide, 2020. Johns Hopkins Guides, www.hopkinsguides.com/hopkins/view/Johns_Hopkins_Diabetes_Guide/547062/all/Hemoglobin_A1c.
Sarkar S, Donner T. Hemoglobin A1c. Johns Hopkins Diabetes Guide. 2020. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_Diabetes_Guide/547062/all/Hemoglobin_A1c. Accessed December 6, 2023.
Sarkar, S., & Donner, T. (2020). Hemoglobin A1c. In Johns Hopkins Diabetes Guide https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_Diabetes_Guide/547062/all/Hemoglobin_A1c
Sarkar S, Donner T. Hemoglobin A1c [Internet]. In: Johns Hopkins Diabetes Guide. ; 2020. [cited 2023 December 06]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_Diabetes_Guide/547062/all/Hemoglobin_A1c.
* Article titles in AMA citation format should be in sentence-case
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