Editing Glycated hemoglobin (section)

==Principle in medical diagnostics==
Glycation of proteins is a frequent occurrence, but in the case of hemoglobin, a nonenzymatic condensation reaction occurs between glucose and the N-end of the [[beta chain]]. This reaction produces a [[Schiff base]] ({{chem2|R\sN\dCHR'}}, R=beta chain, CHR'=glucose-derived), which is itself converted to 1-deoxyfructose. This second conversion is an example of an [[Amadori rearrangement]].{{cn|date=September 2024}}

When blood glucose levels are high, [[glucose]] molecules attach to the hemoglobin in [[red blood cell]]s. The longer hyperglycemia occurs in blood, the more glucose binds to hemoglobin in the red blood cells and the higher the glycated hemoglobin.<ref name="pmid33806493">{{cite journal |vauthors=Pohanka M |title=Glycated Hemoglobin and Methods for Its Point of Care Testing |journal=Biosensors |volume=11 |issue=3 |date=March 2021 |page=70 |pmid=33806493 |doi=10.3390/bios11030070 |doi-access=free |pmc=8000313}}</ref>

Once a hemoglobin molecule is glycated, it remains that way. A buildup of glycated hemoglobin within the red cell, therefore, reflects the average level of glucose to which the cell has been exposed during its [[red blood cell#Life cycle|life-cycle]]. Measuring glycated hemoglobin assesses the effectiveness of therapy by monitoring long-term serum glucose regulation.

A1c is a weighted average of blood glucose levels during the life of the red blood cells (117 days for men and 106 days in women<ref>{{cite journal |last=Unnikrishnan |first=Ranjit |date=Jul–Aug 2012 |title=Drugs affecting HbA1c levels |journal=Indian Journal of Endocrinology and Metabolism |volume=16 |issue=4 |pages=528–531 |pmid=22837911 |doi=10.4103/2230-8210.98004 |doi-access=free |pmc=3401751}}</ref>). Therefore, glucose levels on days nearer to the test contribute substantially more to the level of A1c than the levels in days further from the test.<ref>{{cite web |title=NGSP: HbA1c and eAG |website=ngsp.org |url=https://ngsp.org/A1ceAG.asp |access-date=2024-06-21 |url-status=live |archive-url=https://web.archive.org/web/20151015124504/http://www.ngsp.org/A1ceAG.asp |archive-date=2015-10-15}}</ref>

This is also supported by data from clinical practice showing that HbA1c levels improved significantly after 20 days from start or intensification of glucose-lowering treatment.<ref>{{cite journal |vauthors=Sidorenkov G, Haaijer-Ruskamp FM, de Zeeuw D, Denig P |title=A longitudinal study examining adherence to guidelines in diabetes care according to different definitions of adequacy and timeliness |journal=PLOS ONE |volume=6 |issue=9 |pages=e24278 |year=2011 |bibcode=2011PLoSO...624278S |pmid=21931669 |doi=10.1371/journal.pone.0024278 |doi-access=free |pmc=3169586}}</ref>