HbA1c test Advantages & limitations, let us discuss HB A one C test. What are the advantages and limitations of this test compared with other blood tests for dinosaur of diabetes? We will discuss in this. So, glucose is one of the essential molecule for the source of energy.
But when these glucose levels are excessively increased, it can produce few of the symptoms in the patients, resulting in one of the condition diabetes. So with elevated glucose levels we can observe increased thirst, unexpected tiredness, increased hungriness, increased frequency of urination.
As excess glucose can affect the eye, it can produce some blurred vision, increased risk of infections with increased levels of glucose, and finally, it can also produce unexpected weight loss. All these symptoms can be observed with elevated levels of glucose in the plasma. So, estimation of glucose is essential in order to assess any development of diabetes.
But in few of the patients we can observe asymptomatic phase. That means patients may not have any of these symptoms, but still their glucose levels are excessively elevated. So whether symptomatic or asymptomatic, the elevated levels of glucose levels always produce some damage to the major organs, so they should be strictly controlled.
Further, we require the blood test for glucose, which should be easily available patient complaint and available at reasonable cost. So so many tests are available for a diagnosis as well as for estimation of blood glucose levels.
Among them, FPG is one of the test fasting plasma glucose levels. Second one is the GTT glucose tolerance test and third one is the RPG random plasma glucose test. Here glucose tolerance test is one of the reliable test. In this test, initially one blood sample is going to be collected and immediately a glucose liquid is going to be taken. Then another blood sample can be collected either at one R, two R or three R.
Generally at two R’s, ender blood sample is going to be collected and any excess evaluation of glucose is going to be detected at a two sample. Even this test gives reliable results, but this is one of the time consuming process and requires multiple sampling.
And random plasma glucose tests can be done at any time during the day, but it is not completely reliable because the glucose levels are highly variable with the food intake and other conditions. Finally, FPG fasting plasma glucose is one of the reliable tests for diabetes. And here the fingerprick test is available, which can be done within the home.
So, FPG is one of the easily available tests to assess the glucose levels within the plasma. But still FPG is having few of the limitations. So the patients who are going to take the FPG, they should maintain the fasting conditions.
Food intake should be controlled for the last 8 hours, so eight hour fasting should be maintained in order to assess the proper blood glucose levels. That’s why FPG is done at the early morning without any intake of food.
So any intake of liquids within eight hour fasting may result in the increased levels of FPG values. Similarly, few of the conditions can also reduce the FPG values. For instance, any excessive exercise during the morning or use of any drugs such as antidiabetic agents or insulin within these 8 hours can reduce the FPG values. So even FPG is a easily available test for a diagnosis of diabetes. It is highly variable with fasting conditions, intake of food and fluctuations of glucose levels.
But in case of HBA one C, these conditions are not required. So in case of HB avenc, fasting is not required. So food intake will not influence the HBA and C values. Similarly, it can be done at any time. So not only the morning, at any time of the day, HBMC test can be done.
And this test is not influenced by the fluctuations of glucose levels within the day, because HBMC gives the average glucose levels for past two to three months. Actually, this test is not the direct measurement of the glucose.
Instead, it involves the estimation of glycated glucose levels. That’s why it is not affected by fluctuations of the glucose within the day and it is not affected by intake of the food. That’s why nowadays HBA one C getting more importance in diagnosis of diabetes and prediabetic stages.
So, what is HBA one C? This HBA one C test can also be simply called as a one C test. So here A indicates the hemoglobin type A, which is going to be glycated with the glucose, resulting in the glycated hemoglobin. Now, within the blood vessels, Erythrocytes are present. These erythrocytes contain the hemoglobin.
The lifespan of these Erythrocytes is around two to three months. The maximum lifespan is 120 days. So up to three months, Erythrocytes can exist within the blood vessels. Now, during this lifespan, they are interacting with the glucose. The glucose molecules can enter into the Erythrocytes, where they can interact with the hemoglobin molecules.
So, by binding of glucose to these hemoglobin molecules, they form glycated hemoglobin. But here, all the Erythrocytes are not glycated. We can observe few of the Erythrocytes which are non glycated. So, HBNC test identifies the percentage of glycated hemoglobin versus total hemoglobin present in the plasma. So this is the Erythrocyte which is having hemoglobin molecules.
Now, glucose can enter into the Erythrocytes and it can bind to the hemoglobin. But in order to enter into the Erythrocytes, they should express one of the transporters. They are the gluten transporters. These are the transporter for the glucose. Now, glucose within the plasma can enter into the Erythrocytes through these glutton receptors and it can bind to the hemoglobin.
But the binding of glucose with hemoglobin depends on two factors the availability of hemoglobin, as well as rate and extent of glycation. So HBMC is measured as a percentage, which is a ratio of glycated hemoglobin levels by total hemoglobin levels multiplied by 100.
So this is a percentage of hemoglobin that is going to be glycated with the glucose will give the HBMC values. So any modification of hemoglobin, for instance, in case of hemolysis, hemoglobin may be lost. In such cases, the HBMC values may be reduced similar in the modification of glycation.
Again. HB Evanc values are modified. So when these two factors are not variable, HB avenc gives a good indication of average plasma glucose levels for past two to three months. Now let us see, what are the HB avenc levels? The normal levels of HB avenc are less than 5.7%.
So in such patients we can consider the glucose levels are under control for past two to three months. But sometimes few of the factors may reduce the HBA ONC values, which should also be considered similar. In the people with prediabetic states, the HBA ONC values are variable from 5.7 to 6.4%. So in such patients, cartoon should be taken in order to reduce the development of diabetes. So control of sugar intake and proper exercise conditions can reduce the development of diabetes.
Third, one is a diabetic stage where the A one C values are greater than 6.5%. Again, in such patients, proper diet and exercise should be maintained along with use of antidiabetic agents based on elevation of a one C values. Now let us the limitations of HBMC test. As we have discussed, HBMC values depends on the rate of glycation with hemoglobin, so it depends on the availability of hemoglobin as well as the extent of glycation. Normally, the lifespan of erythrocytes is two to three months.
But when the levels of RBC are going to fall, it reduce the hemoglobin levels resulting in the decreased HBMC values. So if you have the conditions like multiple blood transfusions, severe blood loss, or some of the disorders like chronic renal failure, where hemolysis results in the loss of RBC, all these conditions can reduce the HB avenc values. So in such patients we can observe low HB avenc even with elevated levels of glucose. Similar in conditions like liver failure, we can observe decreased HBMC values. Or in the patients with anemia, again, HBMC values are reduced.
Even the conditions like pregnancy can also affect HB avenc values. When the bilrobial levels are excessively increased, it can increase the glycation process, so it can elevate the HB avenc values. In this way, abnormal A one C values can be produced by many of the conditions which should be closely monitored. Even HBA one C is variable with the ethnicity, so different population may have the different types of hemoglobin. So in this HB A NC hemoglobin type A is going to be used for estimation.
