HbA1c poorly diagnostic for diabetes in Arab population
MedWire News: Using glycated hemoglobin (HbA1c) to test for diabetes yields a high number of false-negatives in people of Arab ethnicity, research shows.
This may lead to "delayed diagnosis and potential progression of diabetes-related complications," suggest Linda Jaber (Wayne State University, Detroit, Michigan, USA) and colleagues in the Journal of Clinical Endocrinology and Metabolism.
HbA1c is recommended by the American Diabetes Association, as well as other major organizations, for the diagnosis of diabetes and prediabetes. However, racial and ethnic variations in HbA1c have been reported.
In this study, Jaber's group examined the sensitivity and specificity of HbA1c for the diagnosis of diabetes and prediabetes in a population-based representative sample of 482 randomly selected Arab adults living in Detroit.
HbA1c testing correctly identified just 5% of individuals diagnosed with diabetes by oral glucose tolerance test, 13% by fasting plasma glucose, and 41% by both criteria.
In addition, HbA1c alone correctly identified 14% of individuals with impaired glucose tolerance, 9% of subjects with impaired fasting glucose levels, and 33% of those with both abnormalities.
Overall, HbA1c had a sensitivity for diagnosing diabetes mellitus of 19%, a specificity of 100%, and an area under the receiver operating characteristic curve (AUC) of 77%.
For the diagnosis of prediabetes, HbA1c had a sensitivity, specificity, and AUC of 14%, 91%, and 57%, respectively.
Using 6.2% as the HbA1c cutoff for diagnosing diabetes yielded the highest accuracy, but still missed 73% of subjects with diabetes.
Similarly, an HbA1c cutoff of 5.1% was most accurate for diagnosing prediabetes, but still missed 31% of patients with the condition.
"There was no difference in age, sex, or BMI between individuals with diabetes that were correctly identified by [HbA1c] compared with those that were not," write Jaber and colleagues.
The researchers nonetheless conclude that, given the practicality of HbA1c, its low diagnostic utility "should not preclude clinicians from using it as a screening tool when obtaining a fasting blood sample is not possible."
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