MONDAY, March 25, 2019 (HealthDay News) -- The prevalence of diabetes mellitus (DM) is underestimated and normal glucose tolerance (NGT) is overestimated using hemoglobin A1c (A1c) criteria, according to a study presented at the annual meeting of The Endocrine Society, held from March 23 to 26 in New Orleans.
Maria Mercedes Chang Villacreses, M.D., from the City of Hope National Medical Center in Duarte, California, and colleagues compared the states of glucose tolerance defined by A1c and by the oral glucose tolerance test (OGTT) in a sample of 9,000 adults from the 2005 to 2014 National Health and Nutrition Examination Survey. The sensitivity and specificity of A1c for DM and NGT were assessed in reference to OGTT.
The researchers observed a significant difference in the distribution of glucose tolerance states defined by A1c and OGTT. The sensitivity and specificity for the diagnosis of DM by A1c were 26.93 and 99.39 percent, respectively, in reference to OGTT. With the A1c criteria, A1c misclassified 73.07 percent of DM defined by OGTT. The sensitivity and specificity of NGT diagnosis by A1c were 84.91 and 43.53 percent, respectively, in reference to OGTT. A1c misclassified 15.09 percent of NGT defined by OGTT using A1c criteria.
"Our results indicated that the prevalence of diabetes and normal glucose tolerance defined solely by A1c is highly unreliable, with a significant tendency for underestimation of the prevalence of diabetes and overestimation of normal glucose tolerance," Chang Villacreses said in a statement.