Hemoglobin A1c: Past, present and future

Hemoglobin Al c (HbAlc) has been used for decades to monitor the control of glycemia in diabetes.Although HbA1c is currently undergoing a reassessment, and major developments have been underwayin recent years, HbA1c is not recommended at present for diabetes screening or diagnosis. The objectiveof this review is to summarize the recent developments and to review a potential diagnostic role forHbAlc. Implementation of changes in HbAlc results and units of measurements have been suggested forthe purpose of test standardization. These include lower reference ranges (by about 1.5-2 points) andmeasurement units expressed in percentage (%), as mg/dL (mmol/L) or mmol/mol (or a combination ofthese units). In diabetes screening and diagnosis, the current diagnostic guidelines use measurement ofplasma glucose either fasting or after glucose load. These diagnostic methods have shortcomings warrantinga potential diagnostic role for HbA1c. While recent developments in HbAlc methodologies areacknowledged, it is not yet known which changes will be implemented, and how soon. Given the recentliterature supporting HbAlc diagnostic abilities, and given the shortcomings of the current guidelines, it ispossible that a diagnostic role for HbA1c may be considered in future practice guidelines, globally. Veryrecently, the first of such recommendations has been proposed by an expert panel, as announced by theUS Endocrine Society.