In Reply Dr Magliano and colleagues raise concern regarding our use of all 3 glycemic markers (hemoglobin A1c, FPG, and 2-hour PG) in defining undiagnosed diabetes, and of the lack of repeat testing in the National Health and Nutrition Examination Survey (NHANES).
We agree that FPG and 2-hour PG may represent complementary pathophysiological processes of diabetes and using both may be logical when defining diabetes. However, hemoglobin A1c is a valid diagnostic marker that is commonly used in clinical practice and has less day-to-day variability than the other markers.1 All 3 markers are associated with diabetes complications.2 Based on this evidence, the American Diabetes Association (ADA) revised its diagnostic criteria in 2010 recommending the addition of hemoglobin A1c as a diagnostic test for diabetes,2 and the World Health Organization (WHO) made a similar revision to its diagnostic criteria in 2011.3
Menke A, Casagrande S, Cowie CC. US Trends for Diabetes Prevalence Among Adults—Reply. JAMA. 2016;315(7):705-706. doi:10.1001/jama.2015.16473