How to Read Hemoglobin Test Results?
Diabetes is one of the oldest non-communicable diseases known to the humanity. Most early civilizations knew about it, be it Egyptian or Asian. About 2500 years back Indians and Asians noted that urine becomes sweet in diabetes, and ants are attracted towards it. For centuries various tests of urine were used to diagnose diabetes(“A Historical Perspective of the Diagnosis of Diabetes,” n.d.).However, tests of urine are not of much use in the early diagnosis of diabetes, which is important to prevent the complications(Wei & Teece, 2006). In the last century, many blood tests were devised, which are more accurate and helpful in early diagnosis of diabetes(“Screening for Type 2 Diabetes-WHO report,” n.d.).
In modern days, diagnosis of diabetes is confirmed mostly by various blood tests, most commonly used blood tests are fasting blood glucose test or random blood glucose test, oral glucose tolerance test, and HbA1c test (often referred just as anA1c test). Blood tests are not only accurate in diagnosis, but they also help us to know how severe is our diabetes(“Diabetes Mellitus: Diagnosis and Screening – American Family Physician,” n.d.). In recent years HbA1c has become one of the most important tests as it offers certain advantages over the other blood tests.
What is HbA1c?
HbA1c or glycated hemoglobin is the test of glucose levels associated with hemoglobin. Yes, we are talking about the same hemoglobin, which gives ared color to our blood or red blood cells. It is a red colored protein that is needed to carry oxygen to various organs of our body. Most people know that deficit of hemoglobin is related to anemia, but the question arises that what does it has to do with diabetes?
On average our red blood cells live for about three months or 12 weeks, and the sugar molecules in our blood have atendency of sticking to the hemoglobin, higher is the level of sugar in our blood, more of it will stick to it. Thus by testing the level of glycation of hemoglobin, we get an average of blood sugar level during last 8 to 12 weeks. This test is especially useful in knowing, how well you are controlling your diabetes, and is an excellent predictor of complications from the high blood sugar levels(“The A1C Test & Diabetes | NIDDK,” n.d., “What is the HbA1C?” n.d.).
What are normal ranges?
Most of the world’s leading organizations agree on what should be considered as normal range and who should be regarded as diabetic, though minor differences may exist between recommendations by various organizations. Recommendations of American Diabetic Association (ADA) are most widely accepted, according to it a diabetic person has a HbA1c level of 6.5% or above(Drive, Arlington, & 1-800-Diabetes, n.d.).
- Normal: less than 5.7% is regarded as completely normal.
- Prediabetes: 7% to 6.4% is prediabetes, it means that a person is at very high risk of developing diabetes, but still glucose level is not high enough to call a person as having diabetes(“Pre-Diabetes Information | Joslin Diabetes Center,” n.d.).
- Diabetes:5% or higher.
HbA1c targets and test frequency
Once the person has been diagnosed with diabetes, it is crucial to control the blood sugar levels to avoid the various complications associated with the disease. HbA1c test is highly versatile in monitoring diabetes(Manley, 2003), as it shows the average of last few weeks. So the question arises, what should be the target for the person who has been already diagnosed with diabetes?
Well, there is no single answer to what should be the ideal target of HbA1c in a diabetic person, your doctor best decides your targets. It is individual to each person and depends on many factors, like age, other diseases along with diabetes, these verity of diabetes, for how long person has been suffering from diabetes and response to the medicines. Ideally, the target must be to have Hb1Ac levels below 6.5%, but this may not be possible in many cases(Brownlee & Hirsch, 2006). Thus in such cases, the doctor may target higher levels, as research has shown that very aggressive treatment may not be suitable in certain cases(Group, 2008; Huang, Liu, Moffet, John, & Karter, 2011). But still, even 1% decrease in HbA1c may reduce therisk of various complications(“What is HbA1c?”, n.d.).
Since this test is an average of last 8-12 weeks, thus it may be done every three months, and in well-controlled diabetes, it may be done twice a year(Practitioners, n.d.).
How does it compare with other blood tests?
The other two blood tests commonly used in diabetes are oral glucose tolerance test and fasting blood glucose, though both these tests have importance, each test has its pros and cons(“Diabetes & Prediabetes Tests | NIDDK,” n.d.).
Oral glucose tolerance test is mostly used to screen or confirm the diagnosis of diabetes, especially when other tests are doubtful, but this test is most uncomfortable to carry out, as is involves drinking a lots of sugary syrup about 2 hours before the test. This test is not of much help in knowing the severity of diabetes in a known diabetic person. Though oral glucose test is still the method of choice in pregnancy(Aekplakorn et al., 2015; “Diabetes & Prediabetes Tests | NIDDK,” n.d.).
Fasting blood glucose test is the most commonly used test to screen for diabetes, confirm the diagnosis, and know about these verity of the disease. This test is also helpful in knowing, how well the person is controlling diabetes, or how well the treatment is helping a person. This test is carried out after 8 hours of fasting. But false results with this test are not uncommon. Fasting blood glucose levels are dependent on how long the person has been fasting, what does the person eat before the fasting, did a person had any stress event during the fasting period.Time of the day when the test is done, and finally what was the time interval between sample collection and laboratory analysis.These large number factors decrease the accuracy of fasting blood glucose test. Moreover, the results of this test may show better glucose levels, if a person has been intensively controlling diabetes for last one week(Ghazanfari, Haghdoost, Alizadeh, Atapour, & Zolala, 2010).
HbA1c being an average of almost about three months gives us a better historical picture of longer duration, it can be done at any time of the day. It does not require fasting, and will not be affected by some short, recent stressful condition, nor will it vary during the day.It may be inaccurate in certain circumstances like if a person is suffering from anemia or diabetes is progressing too quickly. Thus final interpretation is best made by the trained specialist(Bonora & Tuomilehto, 2011; “Diabetes & Prediabetes Tests | NIDDK,” n.d.).
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