HbA1c testing is very common and crucial for people living with diabetes. It refers to glycated or glycosylated haemoglobin that gives us an overall picture of what our average blood sugar levels have been over a period of weeks/months (usually 3 months). The higher the HbA1c, the greater the risk of developing diabetes-related complications.
When the body processes sugar, glucose in the bloodstream naturally attaches to haemoglobin (Hb). The amount of glucose that combines with this protein Hb is directly proportional to the total amount of sugar that is in your system at that time. Because red blood cells in the human body survive for 8-12 weeks before renewal, measuring glycated haemoglobin (HbA1c) can be used to reflect average blood glucose levels over that duration, providing a useful longer-term gauge of blood glucose control. If your blood sugar levels have been high in recent weeks, your HbA1c will also be greater.
HbA1c targets
Targets for HbA1c are as follows:
* For people without diabetes, the range is 20-41 mmol/mol (4-5.9%). For people with diabetes, an HbA1c level of 48 mmol/mol (6.5%) is considered good control, although some people may prefer their numbers to be closer to that of non-diabetics.
* For people at greater risk of hypoglycemia (lower than normal blood sugar), a target HbA1c of 59 mmol/mol (7.5%) to reduce the risk of hypoglycemia.
* HbA1c levels between 5.7% and 6.4% indicate increased risk of diabetes (prediabetes).
In some studies, high HbA1c indicating poorer diabetes control has been associated with serious, long-term diabetic complications including: heart attack, retinopathy (blindness), diabetic nephropathy (kidney failure).
Research has also shown that people with type 2 diabetes who reduce their HbA1c level by 1% are:
* 19% less likely to suffer cataracts
* 16% less likely to suffer heart failure and
* 43% less likely to suffer amputation or death due to peripheral vascular disease
When should HbA1c levels be tested?
Everyone with diabetes mellitus should be offered an HbA1c test at least once a year. Some people may have an HbA1c test more often. This may be more likely if you have recently had your medication changed or your health team are otherwise wishing to monitor your diabetes control more than once a year.

The write up is compiled by Dr Shahjada Selim, Endocrinologist, Comfort Doctors Chamber, Dhaka. Email: [email protected]