Lexicon
HbA1c
Also known as Hemoglobin A1c, Glycated Hemoglobin
Definition
HbA1c (glycated hemoglobin) is an important indicator of long-term glycemic control that reflects the cumulative glycemic history of the preceding two to three months, and it correlates well with the risk of long-term diabetes complications. [1] Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased HbA1c in the blood, and HbA1c is also used to monitor glycemic control. [2] The American Diabetes Association has recommended glycated hemoglobin as a possible substitute for fasting blood glucose in the diagnosis of diabetes. [1]
How it works
HbA1c is the reference test for long-term glucose monitoring, providing a reliable measure of chronic hyperglycemia over time. [3] Because it integrates glycemia over months rather than a single instant, HbA1c does not reflect the intra- and inter-day glycemic excursions that continuous glucose monitoring can capture. [4]
Connected concepts
How it's measured
HbA1c test results are standardized to the International Federation of Clinical Chemistry (IFCC) Reference Measurement Procedure in harmony with the National Glycohemoglobin Standardization Program (NGSP), and strict standardization enables universal reference values and clinical decision limits. [5] HbA1c is not recommended in several situations such as hemoglobinopathies, pregnancy, or chronic kidney disease, where the result can be unreliable and alternative measures of glycemia should be used. [3]
What levels mean
Prediabetes is defined in part by a glycated hemoglobin level of 5.7% to 6.4%. [6] The American Diabetes Association has recommended HbA1c with a cut-point of 6.5% or higher for diagnosing diabetes as an alternative to fasting-plasma-glucose-based criteria. [1] For most people living with diabetes an HbA1c target of 7.0% or lower (53 mmol/mol) is recommended, with a tighter target of 6.5% or lower (48 mmol/mol) encouraged for those who have access to advanced diabetes technologies such as continuous glucose monitoring and automated insulin
Community knowledge
## Redefining Normal Ranges
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- 1.Sherwani SI, Khan HA, Ekhzaimy A, Masood A, Sakharkar MK. Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients. Biomark Insights · 2016
- 2.Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvath AR, Lernmark Å, Metzger BE, Nathan DM. Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus. Diabetes Care · 2023
- 3.Zendjabil M. Glycated albumin. Clin Chim Acta · 2020
- 4.Danne T, Nimri R, Battelino T, Bergenstal RM, Close KL, DeVries JH, Garg S, Heinemann L. International Consensus on Use of Continuous Glucose Monitoring. Diabetes Care · 2017
- 5.Weykamp C. HbA1c: a review of analytical and clinical aspects. Ann Lab Med · 2013
- 6.Echouffo-Tcheugui JB, Perreault L, Ji L, Dagogo-Jack S.
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