Clinical significance and application of glycated hemoglobin
Glycated hemoglobin (GHb) is a product formed by the non-enzymatic action of blood glucose through the cell membrane and hemoglobin-chain proline in red blood cells, and the synthesis rate is proportional to the concentration of sugar in the environment where red blood cells are located.
The formation of glycated hemoglobin is irreversible, and its concentration is related to the red blood cell life (average 120 days) and the average concentration of blood glucose during this period. It is not affected by fluctuations in daily plasma glucose concentration, and is not affected by exercise or food, so glycation Hemoglobin reflects the average blood glucose concentration over the past 6-8 weeks, which provides a reliable laboratory indicator for assessing blood glucose control.
The so-called HbAlc is a component of the chromatographic separation of Hb. It is not a specific substance. Only Hb combined with glucose is called Glyco-sylated Hemoglobin (GHb). Now, HbA1c and GHb are clinically regarded. Is synonymous.
The difference between HbA1c and blood sugar
Blood sugar is broken down from carbohydrates in food. Monosaccharides in the blood usually refer only to glucose. The blood glucose test results reflect immediate blood sugar levels.
The glycated hemoglobin test usually reflects the patient's blood glucose control for nearly 8 to 12 weeks. Glycated hemoglobin is the "gold standard" for new diagnostic criteria and therapeutic monitoring of diabetes.
Fasting blood glucose and postprandial blood glucose reflect the blood sugar level at a specific time and are easily affected by factors such as eating and glucose metabolism. Glycated hemoglobin can stably and reliably reflect the average blood glucose level within 120 days before the test, and is subjected to blood draw. Time, whether it is fasting, whether using insulin or other factors does not interfere.
The characteristics of glycated hemoglobin determine its significance in diabetes monitoring:
(1) Parallel to the blood glucose level. The higher the blood sugar, the higher the glycated hemoglobin, so it can reflect the level of blood sugar control.
(2) The generation is slow. Because blood sugar is constantly fluctuating, each blood draw can only reflect the blood sugar level at that time, while glycated hemoglobin is gradually formed. The short-term increase of blood sugar does not cause the increase of glycated hemoglobin; in turn, the short-term blood sugar lowering Will not cause a decrease in glycated hemoglobin. Since the meal does not affect its measurement, it can be measured after the meal.
(3) Once generated, it is not easy to decompose. Glycated hemoglobin is quite stable and difficult to decompose, so although it can not reflect the fluctuation of blood glucose in the short term, it can reflect the degree of glycemic control for a long time. Glycated hemoglobin can reflect the average blood glucose level within 2 months before blood collection.
(4) Less affected by hemoglobin levels. Glycated hemoglobin refers to its proportion in total hemoglobin and is therefore unaffected by hemoglobin levels.
Good glycemic control is the key to preventing complications
International large-scale clinical trials have concluded that glycosylated hemoglobin levels can be significantly reduced and the risk of complications is significantly reduced in patients with diabetes after intensive treatment.
However, if the long-term control of glycated hemoglobin is unstable, its effects will be multifaceted:
It changes the affinity of red blood cells for oxygen and accelerates the formation of cardiovascular and cerebrovascular complications; if the crystals in the eye are saccharified, it can cause cataracts. In addition, it can cause thickening of the glomerular basement membrane, induce diabetic nephropathy, and cause an increase in blood lipids and blood viscosity. Elevated glycated hemoglobin is a high risk factor for myocardial infarction and stroke death. Glycated hemoglobin increases and the relative risk of mortality increases.
Therefore, glycated hemoglobin is a very important monitoring indicator for diabetic patients, and its level directly determines the occurrence and development of various chronic diseases that seriously affect diabetes patients. Regular monitoring of glycated hemoglobin in diabetic patients is of great importance to help patients improve their glycemic control levels and to promote blood glucose levels in patients, thereby reducing the incidence of complications.