Glycosylated hemoglobin, often referred to simply as HbA1c or A1C, measures average blood sugar levels (all ups and downs) in the last two to three months. The purpose of the A1C test is to give you a feeling of control of blood sugar levels. This is reported as a percentage.
AlC is glucose bound to hemoglobin, a protein found in red blood cells that transfer oxygen from the lung to all other parts of the body.
Hemoglobin consists of four globin chains (proteins); two beta (b) and two alpha (a) chains. Each chain has a bound hem, an oxygen binding site for hemoglobin.
A1C is hemoglobin that is glycolized or modified by the addition of glucose. Sometimes called glycated hemoglobin A1c or glycated hemoglobin.
Your aim should be to keep your hemoglobin A1C level as close as possible to your target level. You and your doctor can work on this to define your safe target level.
The American Diabetes Association recommends that most people receive their A1C up to 7 percent or less. Other diabetes organizations, such as the International Federation of Diabetes, propose 6.5 percent.
Glucose in A1C is irreversibly linked to one or both of the beta chain hemoglobins. During the life of red blood cells, glucose is continuously bound to hemoglobin. Since the presence of circulating red blood cells for about 120 days, A1C is the average blood sugar level in the blood for about 120 days.
However, the blood glucose level in the last 30 days significantly contributes to the blood levels of A1 up to 90 to 120 days earlier. This explains why A1C levels can be increased or decreased relatively rapidly if the blood sugar level changes greatly; does not take 120 days to detect clinically significant changes in the A1C after a clinically significant change in mean blood sugar levels.
The normal A1C level in people without diabetes is about 4% to 6%. After the discovery of A1C in 1967 and the fact that people with diabetes had higher levels of A1C, the clinical and biological significance of these modified hemoglobins continued to be clarified.
Mechanisms of damage
Glycated hemoglobin causes the growth of highly reactive free radicals in the blood vessels. Radicals alter the membrane properties of blood cells. This leads to an aggregation of blood cells and increased blood viscosity, which leads to reduced blood flow.
Another type of glycosylated Hb causes inflammation that leads to the formation of atherosclerotic plaque (atheroma). The development of free radicals induces the excitation of Fe2 + -Hb by Fe3 + -Hb in an abnormal Hb ferrule (Fe4 + -Hb). Fe4 + is unstable and reacts with specific amino acids in Hb to obtain the oxidation state of Fe3 +. The Hb molecule is aggregated with each other via cross-linking reactions and these cells Hb (multimers) cause cell damage and release Hb + FE4 the array of arteries and veins deeper (sub-endothelial). This results in an increased bandwidth of the endothelial blood vessel and production of monocyte adhesion to the anti-inflammatory protein, which stimulates macrophage accumulation on the surface of blood vessels, ultimately leading to deleterious plaques in these vessels.
Hb-AGE high glycemic passes through the vascular smooth muscle layer and inactivates the endothelium-dependent relaxation induced by acetylcholine, possibly by binding to the nitric oxide (NO) to prevent its normal function. NO is a potent vasodilator and also inhibits the formation of a plaque that promotes LDL (oxidized form) (i.e., “bad cholesterol”).
This total degeneration of blood cells also releases the heme from them. Loose heme can cause oxidation of endothelial and LDL proteins, resulting in plaques.