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.