Implications of Using Hemoglobin A1C for Diagnosing Diabetes Mellitus

Abstract

Until 2010 the diagnosis of diabetes mellitus was based solely on glucose concentration, but American Diabetes Association (ADA) recommendations now include a new criterion: hemoglobin A1C ≥6.5%. Because this change may have significant implications for diabetes diagnosis, we conducted a comprehensive literature review including peer-reviewed articles not referenced in the ADA report.We conclude that A1C and plasma glucose tests are frequently discordant for diagnosing diabetes. A1C ≥6.5% identifies fewer individuals as having diabetes than glucose-based criteria. Convenience of A1C test might increase the number of patients diagnosed, but this is unproven. Diagnostic cut-points for both glucose and A1C are based on consensus judgments regarding optimal sensitivity and specificity for the complications of hyperglycemia. A1C may not accurately reflect levels of glycemia in some situations, but in comparison with glucose measurements, it has greater analytic stability and less temporal variability. When choosing a diagnostic test for diabetes, the limitations of each choice must be understood. Clinical judgment and consideration of patient preference are required to appropriately select among the diagnostic alternatives.

The cutoffs and performance of glycated hemoglobin for diagnosing diabetes and prediabetes in a young and middle-aged population and in an elderly population

“…Compared with plasma glucose, HbA1c is more reproducible, provides a better reflection of chronic glucose exposure and correlates well with diabetes-related complications [12][13][14][15]. Although the role of HbA1c as a diagnostic indicator was recognized, more longitudinal epidemiological studies have reported that demographic and ethnic factors may contribute to complications in using HbA1c for the diagnosis of diabetes, and the optimal diagnostic HbA1c cutoff of is debated and varies due to genetic and biological variations [16][17][18].…”

Relationship Between HbA1c and Complex Regional Pain Syndrome in Stroke Patients With Type 2 Diabetes Mellitus

“…Glycosylated hemoglobin A (HbA1c) is an index of blood glucose control, and it reflects the average blood glucose level for 2 to 3 months [910]. Normal HbA1c is below 6%, but it exceeds 6% in diabetes and can increase up to 10%–12% [11].…”

Glucose control in diabetes: which target level to aim for?

“…In fact, there is not perfect concordance between results using the HbA 1c method and the FPG and 2-h PG tests. On the basis of a recent comprehensive literature review, it was concluded that HbA 1c ‡ 6.5% identifies fewer individuals with diabetes than glucose-based criteria [23]. HbA 1c has lower sensitivity, and it may inaccurately reflect glycaemia in the presence of certain anaemias and haemoglobinopathies [16].…”