Utility of Hemoglobin A1c for Diagnosing Prediabetes and Diabetes in Obese Children and Adolescents

Abstract

OBJECTIVEHemoglobin A1c (A1C) has emerged as a recommended diagnostic tool for identifying diabetes and subjects at risk for the disease. This recommendation is based on data in adults showing the relationship between A1C with future development of diabetes and microvascular complications. However, studies in the pediatric population are lacking.RESEARCH DESIGN AND METHODSWe studied a multiethnic cohort of 1,156 obese children and adolescents without a diagnosis of diabetes (male, 40%/female, 60%). All subjects underwent an oral glucose tolerance test (OGTT) and A1C measurement. These tests were repeated after a follow-up time of ∼2 years in 218 subjects.RESULTSAt baseline, subjects were stratified according to A1C categories: 77% with normal glucose tolerance (A1C <5.7%), 21% at risk for diabetes (A1C 5.7–6.4%), and 1% with diabetes (A1C >6.5%). In the at risk for diabetes category, 47% were classified with prediabetes or diabetes, and in the diabetes category, 62% were classified with type 2 diabetes by the OGTT. The area under the curve receiver operating characteristic for A1C was 0.81 (95% CI 0.70–0.92). The threshold for identifying type 2 diabetes was 5.8%, with 78% specificity and 68% sensitivity. In the subgroup with repeated measures, a multivariate analysis showed that the strongest predictors of 2-h glucose at follow-up were baseline A1C and 2-h glucose, independently of age, ethnicity, sex, fasting glucose, and follow-up time.CONCLUSIONSThe American Diabetes Association suggested that an A1C of 6.5% underestimates the prevalence of prediabetes and diabetes in obese children and adolescents. Given the low sensitivity and specificity, the use of A1C by itself represents a poor diagnostic tool for prediabetes and type 2 diabetes in obese children and adolescents.

2. Classification and Diagnosis of Diabetes

“…Therefore, it remains unclear if A1C and the same A1C cut point should be used to diagnose diabetes in children and adolescents (4,5).…”

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“…HbA1c was used as a diagnostic tool to measure glycaemic control [17]. An HbA1c “A1C Now+”™ point-of-care assay provided quantitative measurement of the % of glycated haemoglobin over the last 3 months.…”

2. Classification and Diagnosis of Diabetes

“…Therefore, it remains unclear if A1C and the same A1C cut point should be used to diagnose diabetes in children and adolescents (3)(4)(5).…”