Glycated hemoglobin

Glycated hemoglobin
MedlinePlus003640
eMedicine2049478
LOINC41995-2

Glycated hemoglobin (also called glycohemoglobin or glycosylated hemoglobin) is a form of hemoglobin (Hb) that is chemically linked to a sugar.

Most monosaccharides, including glucose, galactose, and fructose, spontaneously (that is, non-enzymatically) bond with hemoglobin when they are present in the bloodstream. However, glucose is only 21% as likely to do so as galactose and 13% as likely to do so as fructose, which may explain why glucose is used as the primary metabolic fuel in humans.[1][2]

The formation of excess sugar-hemoglobin linkages indicates the presence of excessive sugar in the bloodstream and is an indicator of diabetes or other hormone diseases in high concentration (HbA1c >6.4%).[3] A1c is of particular interest because it is easy to detect. The process by which sugars attach to hemoglobin is called glycation and the reference system is based on HbA1c, defined as beta-N-1-deoxy fructosyl hemoglobin as component.[4]

There are several ways to measure glycated hemoglobin, of which HbA1c (or simply A1c) is a standard single test.[5] HbA1c is measured primarily to determine the three-month average blood sugar level and is used as a standard diagnostic test for evaluating the risk of complications of diabetes and as an assessment of glycemic control.[5][6] The test is considered a three-month average because the average lifespan of a red blood cell is three to four months. Normal levels of glucose produce a normal amount of glycated hemoglobin. As the average amount of plasma glucose increases, the fraction of glycated hemoglobin increases in a predictable way. In diabetes, higher amounts of glycated hemoglobin, indicating higher of blood glucose levels, have been associated with cardiovascular disease, nephropathy, neuropathy, and retinopathy.[7]

  1. ^ Bunn HF, Higgins PJ (July 1981). "Reaction of monosaccharides with proteins: possible evolutionary significance". Science. 213 (4504): 222–4. Bibcode:1981Sci...213..222B. doi:10.1126/science.12192669. PMID 12192669.
  2. ^ McPherson JD, Shilton BH, Walton DJ (March 1988). "Role of fructose in glycation and cross-linking of proteins". Biochemistry. 27 (6): 1901–7. doi:10.1021/bi00406a016. PMID 3132203.
  3. ^ Pongudom, Saranya (1 November 2019). "Determination of Normal HbA1C Levels in Non-Diabetic Patients with Hemoglobin E". Annals of Clinical & Laboratory Science. 49 (6): 804–9. PMID 31882432.
  4. ^ Miedema K (2005). "Standardization of HbA1c and Optimal Range of Monitoring". Scandinavian Journal of Clinical and Laboratory Investigation. 240: 61–72. doi:10.1080/00365510500236143. PMID 16112961. S2CID 30162967.
  5. ^ a b Elizabeth Weiser Caswell Diabetes Institute. Hemoglobin A1c Fact Sheet. Accessed 2024-07-02.
  6. ^ "2. Glycated haemoglobin (HbA1c) for the diagnosis of diabetes". Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus: Abbreviated Report of a WHO Consultation. WHO Guidelines Approved by the Guidelines Review Committee. World Health Organization. 2011. PMID 26158184. NBK304271.
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