Understanding Diabetes: What Is HbA1c?

HbA1c refers to glycated haemoglobin, which identifies average plasma glucose concentration. 

HbA1c occurs when haemoglobin joins with glucose in the blood. Haemoglobin molecules make up the red blood cells in the blood stream.

When glucose sticks to these molecules it forms a glycoslated haemoglobin molecule – also known as A1c and HbA1c. The more glucose found in the blood, the more haemoglobin will be present. 

How does HbA1c return an accurate average measurement?

Due to the fact that red blood cells survive for 8-12 weeks before renewal, by measuring HbA1c an average blood glucose reading can be returned. For non-diabetics, the usual reading is 3.5-5.5%. For people with diabetes, an HbA1c level of 6.5% is considered good control, although some prefer numbers closer to non-diabetic. 

How does HbA1c differ from blood glucose level?

HbA1c is a longer-term average that is sent to a laboratory and usually conducted in hospital clinics.

Blood glucose is a current reading taken either by a healthcare professional or at home by an individual with diabetes using a glucometer.

When should HbA1c level be tested?

How often HbA1c levels should be taken depends on the person with diabetes and their history of control and treatment objectives.

Generally, the following are considered best practice in HbA1c regularity.

1. Once per 3 months if trying to get better control.
2. Once per 6 months if good control achieved and maintained.

There is little point in having HbA1c checked regularly if you are not making efforts to control your diabetes. Although HbA1c level alone does not predict diabetes complications, good control is known to lower the risk of complication.

How does an HbA1c show poorly controlled diabetes?

In well-controlled diabetes without a high level of glucose in the blood, a lower level of glycosylated haemoglobin will be returned.

If people with type 2 diabetes reduce their HbA1c level by 1%, there is a:

• 19% reduction is cataract extractions
• 16% decrease in heart failure
• 43% reduction in amputation or death due to peripheral vascular disease

In the case of poor control, with more glucose, a higher level of glycosylated haemoglobin will be returned.

But glucose levels change all the time, don't they? 

Blood glucose levels fluctuate constantly, literally on a minute by minute basis. Therefore, for micro adjustments and regular checking, blood glucose testing is advised. The HbA1c level changes very slowly over a 10 week period and is a more accurate method of determining blood sugar control.

From Diabetes.co.uk