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Evidence summaries

Diagnosis of Diabetes Mellitus Using Glycosylated Hemoglobin Levels

Measurement of haemoglobin A1c may be useful in identifying treatment-requiring diabetes, but the sensitivity of the test as the only examination may not be sufficient. Of subjects with haemoglobin A1c level of at least 7%, 89.1 had diabetes, 7.1% had impaired glucose tolerance and 3.8% were normal by modified WHO criteria. Level of evidence: "C"

A systematic review 1 including 18 studies with a total of 11,276 subjects was abstracted in DARE. For those patients whose oral glucose tolerance test results met the criteria for diabetes, the sensitivity, specificity and positive predictive values (assuming a 6% prevalence of diabetes) for mean haemoglobin A1c levels (+ 2 standard deviations) were 66%, 98% and 63% respectively. For mean HbA1c levels (+ 4 standard deviations) the sensitivity, specificity and positive predictive values were 36%, 100% and 97% respectively.

Comment: The quality of evidence is downgraded by potential reporting bias. 16 out of 34 published studies comparing the OGT test and HbA1c were unavailable and therefore the results may be biased.

    References

    • Peters AL, Davidson MB, Schriger DL, Hasselblad V. A clinical approach for the diagnosis of diabetes mellitus: an analysis using glycosylated hemoglobin levels. Meta-analysis Research Group on the Diagnosis of Diabetes Using Glycated Hemoglobin Levels. JAMA 1996 Oct 16;276(15):1246-52. [PubMed] [DARE]

Primary/Secondary Keywords