Reference intervals for HbA1c partitioned for gender and age: a multicenter study

Most recent estimates indicate that 8.8 % of adults (415 million people) have diabetes, and the number of people with the disease is set to rise beyond 642 million in <25 years. This disease is often asymptomatic in its early stages and can remain undetected for several years [1], thus causing the onset of micro-vascular and macro-vascular complications, such as retinopathy, kidney failure, limb amputation and cardiovascular diseases [2], which are the most common cause of death and disability among people with diabetes. In order to minimize the risk of these complications and associated healthcare costs, the early detection and management of diabetes and prediabetes is imperative [1]. According to the WHO, glycated haemoglobin (HbA1c) values between 6.0 and 6.5 % (42–47 mmol/mol) indicate a high risk for the onset of diabetes. Moreover, the International Expert Committee (IEC) recommends that subjects with an HbA1c value within this range should be given interventions; while the American Diabetes Association (ADA) recommends lower HbA1c levels (5.6–6.5 %; 38–47 mmol/mol), together with other tests, to define prediabetes. We currently use the reference ranges recommended by the ADA, but these may be unsuitable for the European population. Furthermore, we recently showed that there is a significant difference in mean HbA1c values measured in healthy donors based on gender [3]. In this context, it seemed interesting to investigate whether there are significant differences in HbA1c values measured in non-diabetic donors not only by gender but also by age.