Introduction:
HbA1c levels refer to the levels of glycated hemoglobin present in the
blood. These levels are used to represent the average plasma glucose of
the person over the previous 8 to 12 weeks 1. It is
also commonly used to determine whether someone is suffering from
diabetes or not. More recently, there has been a substantial amount of
interest in using it as a diagnostic test for diabetes, alongside using
it as a screening test for those at a great risk of developing
diabetes2.
It is believed that HbA1c levels are viewed as a risk factor for
postoperative complications of cardiac surgery and these procedures can
result in increased glycated hemoglobin levels, which are associated
with increased morbidity and mortality rates. Despite this, some papers
state that the increased HbA1c levels cannot be directly attributed as
the causes of increased mortality and morbidity 3. A
recent and large meta-analysis reported that a higher HbA1c
concentrations are frequently linked with the presence of other
metabolic disorders, such as hypertension, dyslipidaemia and obesity,
which are in fact the real problems causing an increased risk of poor
clinical outcomes. 3
These beliefs, however, can be viewed as controversial as some other
studies showed that diabetes and raised HbA1c levels were independently
associated with a higher risk of adverse outcomes 4.
The whole process behind surgical procedures can place a great deal of
physical stress on patients and thus impaired glucose metabolisms
therefore worsen diabetes status. Those suffering with diabetes and
chronic hyperglycaemia, determined by their HbA1c levels, may be at
particular risk at suffering from perioperative morbidity from
diabetes-related complications such as wound infections and renal
dysfunction 5-7.