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15-11-2011 | Diabetes | Article

HbA1c diagnostic threshold set for Middle-Eastern population


Free abstract

MedWire News: Glycated hemoglobin (HbA1c) is a suitable test for the diagnosis of diabetes in the Abu Dhabi population, show study findings.

"This study is the first in a Middle-Eastern population to screen at population level using HbA1c and has been shown to be representative," write Cother Hajat (Department of Public Health and Research, Abu Dhabi, United Arab Emirates [UAE]).

The team sought to validate HbA1c and random glucose against the "gold standard" for diagnosing diabetes, namely, oral glucose tolerance test (OGTT) according to World Health Organization criteria.

They studied 1028 individuals who had been screened during the Weqaya program in April 2008, which was designed to assess cardiovascular disease risk factors in the UAE population.

Participants with an HbA1c of 6.1% or more or a random glucose of 11.1 mmol/L or more underwent follow-up measurement of fasting glucose, OGTT, and HbA1c.

As reported in the journal Diabetes Care, an HbA1c threshold of 6.5%, as recommended by the American Diabetes Association (ADA), diagnosed diabetes in 216 (16%) individuals.

The authors measured the sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC) for various thresholds of HbA1c, against OGTT as the reference test.

The results revealed that the HbA1c threshold of 6.4% had the highest AUC, at 0.78, with sensitivity of 72.0% and specificity of 84.3%.

The corresponding figures for the 6.5% threshold were 0.77, 65.6%, and 89.1%.

Using the 6.4% threshold, HbA1c would have correctly diagnosed diabetes in 72% of patients and incorrectly diagnosed it in 16%.

"Because HbA1c has now been recommended for use as a diagnostic test, specificity is increasingly important, and the threshold of 6.4% in this study provides a high specificity without too much compromise of sensitivity," say Hajat et al.

They say the study has demonstrated the utility of HbA1c for diagnosing diabetes and shown that 6.4% is an optimum HbA1c threshold for the UAE population.

"This is a major step in the fight to tackle the increasing burden of diabetes in the UAE," write the researchers.

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By Sally Robertson