The Utility of HbA1c as a Diagnostic Criterion of Diabetes

Abstract

BackgroundHemoglobin A1c (HbA1c) was adopted as a new standard criterion for diagnosing diabetes. We investigated the diagnostic utility of HbA1c by comparing the 2003 American Diabetes Association (ADA) diagnostic criteria of diabetes with HbA1c of 6.5%. Furthermore, the cut-off value for HbA1c was investigated using receiver operating characteristic curves.MethodsThis study included 224 subjects without a history of diabetes that had a fasting plasma glucose level of above 100 mg/dL. The subjects had undergone a 75 g oral glucose tolerance test, and diabetes was defined as according to 2003 ADA criteria.ResultsThe prevalence of newly diagnosed diabetes was 58.2% by the 2003 ADA criteria, and 47.8% by HbA1c of 6.5%, which underestimated the prevalence of diabetes. Compared with the 2003 ADA criteria, the sensitivity and specificity of HbA1c of 6.5% were 73.5% and 89.1%, respectively. The kappa index of agreement between 2003 ADA and HbA1c criteria was 0.60. The cut-off point of HbA1c for diagnosing diabetes was 6.45% (sensitivity, 73.3%; specificity, 88.2%; area under the curve, 0.85). HbA1c was significantly associated with fasting glucose (r = 0.82, P < 0.01), postprandial glucose (r = 0.78, P < 0.01), and homeostasis model assessment of insulin resistance (r = 0.16, P < 0.05).ConclusionFor high risk patients whose fasting glucose was more than 100 mg/dL, HbA1c criterion underestimated the prevalence of newly diagnosed diabetes compared to the 2003 ADA criteria, and showed moderate agreement. The cut-off value for HbA1c was 6.45%, which was similar to the recommended diagnostic criterion of HbA1c by the 2009 ADA.

Derivation & validation of glycosylated haemoglobin (HbA1c) cut-off value as a diagnostic test for type 2 diabetes in south Indian population

“…Several studies have computed different HbA 1c cut-off values for diagnosing diabetes mellitus based on OGTT ranging from ≥5.6 per cent (38 mmol/mol) to ≥7.0 per cent (53 mmol/mol)14151617181920. Several factors such as age, ethnicity, genetic makeup, erythrocyte lifespan and erythrocyte environment, which can influence glycosylation of haemoglobin2122232425, are likely to have contributed to these differences.…”

Optimal cut-off values for the homeostasis model assessment of insulin resistance (HOMA-IR) and pre-diabetes screening: Developments in research and prospects for the future

“…Epidemiological studies have shown that about 25% of the population has IR and that the prevalence of IR is more than 80% in patients with T2DM (11)(12)(13). Guidelines for primary prevention of T2DM should identify categories of increased risk for DM (pre-DM), but many do not include the cut-off values of IR (14,15).…”

Can A1C Replace Oral Glucose Tolerance Test in the Evaluation of Patients with Impaired Fasting Glucose?

“…Even though some reports propose that HbA1c is useful as a diagnostic criterion of diabetes [7,8,11,39] others suggest that its diagnostic usefulness is inferior to standard testing because of a low sensitivity (26,(40)(41)(42). Our study showed that only 28.6% of the patients with levels of A1C ≥ 6.5% had 2-hPG >11.1 mmol/L.…”