Monday, 11 August 2014

Why HbA1c?

Haemoglobin is the oxygen-carrying pigment that gives blood its red colour and is also the predominant protein in red blood cells. About 90% of haemoglobin is haemoglobin A (the "A" stands for adult type). Although one chemical component accounts for 92% of haemoglobin A, approximately 8% of haemoglobin A is made up of minor components that are chemically slightly different. These minor components include haemoglobin A1c, A1b, A1a1, and A1a2. Hemoglobin A1c (HbA1c) is a minor component of haemoglobin to which glucose is bound. HbA1c also is sometimes referred to as glycosylated or glycosylated hemoglobin or glycohaemoglobin.

In addition to random fasting blood glucose levels, HbA1c levels are routinely measured in the monitoring of people with diabetes. HbA1c levels depend on the blood glucose concentration. That is, the higher the glucose concentration in blood, the higher the level of HbA1c. Levels of HbA1c are not influenced by daily fluctuations in the blood glucose concentration but reflect the average glucose levels over the prior six to eight weeks. Therefore, HbA1c is a useful indicator of how well the blood glucose level has been controlled in the recent past (over two to three months) and may be used to monitor the effects of diet, exercise, and drug therapy on blood glucose in people with diabetes.

In healthy people the HbA1c level is less than 6% of total hemoglobin. Studies have demonstrated that the complications of diabetes can be delayed or prevented if the HbA1c level can be kept below 7%. It is recommended that treatment of diabetes be directed at keeping an individual’s HbA1c level as close to normal as possible (<6%) without episodes of hypoglycemia (low blood glucose levels).

The following are the results when A1c is being used to diagnose diabetes:
  • Normal (no diabetes): Less than 5.6%
  • Pre-diabetes: 5.6% to 6.4%
  • Diabetes: 6.5% or higher

If you have diabetes, you and your doctor or nurse will discuss the correct range for you. For many people the goal is to keep your level below 7%.

The test result may be incorrect in people with anemia, kidney disease, or certain blood disorders (thalassemia). Talk to your doctor if you have any of these conditions. Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results. Abnormal results mean that you have had a high blood sugar level over a period of weeks to months.
  • If your A1c is above 6.5% and you do not already have diabetes, you may be diagnosed with diabetes.
  • If your level is above 7% and you have diabetes, it often means that your blood sugar is not well controlled. Your target A1c should be determined by you and your health care provider. 
The higher your A1c, the higher the risk that you will develop problems such as:
  • Eye disease
  • Heart disease
  • Kidney disease
  • Nerve damage
  • Stroke
If your A1c stays high for a long period, the risk of these problems is even greater. Ask your doctor how often you should have your level tested. Usually, doctors recommend testing every 3 or 6 months.
Other names for this test includes: HbA1C test: Glycated hemoglobin test; Glycosylated hemoglobin test; Hemoglobin glycosylated test; Glycohemoglobin test.

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