J Korean Med Sci.  2018 Mar;33(12):e93. 10.3346/jkms.2018.33.e93.

HbA1c Cutoff for Prediabetes and Diabetes Based on Oral Glucose Tolerance Test in Obese Children and Adolescents

  • 1Department of Pediatrics, Korea University Guro Hospital, College of Medicine, Korea University, Seoul, Korea.
  • 2Department of Pediatrics, The Catholic University of Korea Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.
  • 3Department of Pediatrics, Inje University Ilsan Paik Hospital, Goyang, Korea. pedendo@snubh.org
  • 4Department of Pediatrics, Korea University Ansan Hospital, College of Medicine, Korea University, Ansan, Korea.
  • 5Department of Pediatrics, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
  • 6Department of Pediatrics, Korea University Anam Hospital, College of Medicine, Korea University, Seoul, Korea.


Oral glucose tolerance test (OGTT) is a traditional diagnostic tool for diabetes. Hemoglobin A1c (HbA1c) is an alternative method used in adults; however, its application in youths has been controversial. We evaluated the diagnostic performance of HbA1c and determined optimal cutoff points for detecting prediabetes and diabetes in youth.
This retrospective study included 389 obese children (217 boys, 55.8%) who had undergone simultaneous OGTT and HbA1c testing at six hospitals, Korea, between 2010 and 2016. Subjects were diagnosed with diabetes (fasting glucose ≥ 7.0 mmol/L; 2-hour glucose ≥ 11.1 mmol/L) or prediabetes (fasting glucose 5.6-6.9 mmol/L; 2-hour glucose 7.8-11.0 mmol/L). The diagnostic performance of HbA1c for prediabetes and diabetes was determined using the area under the receiver operating characteristic curve (AUC).
At diagnosis, 197 (50.6%) subjects had normoglycemia, 121 (31.1%) had prediabetes, and 71 (18.3%) had diabetes. The kappa coefficient for agreement between OGTT and HbA1c was 0.464. The optimal HbA1c cutoff points were 5.8% (AUC, 0.795; a sensitivity of 64.1% and a specificity of 83.8%) for prediabetes and 6.2% (AUC, 0.972; a sensitivity of 91.5% and a specificity of 93.7%) for diabetes. When HbA1c (≥ 6.2%) and 2-hour glucose level were used to diagnose diabetes, 100% were detected.
Pediatric criteria for HbA1c remain unclear, therefore, we recommend the combination of fasting and 2-hour glucose levels, in addition to HbA1c, in the diagnosis of childhood prediabetes and diabetes.


Diabetes Mellitus; Diagnosis; Glucose Tolerance Test; HbA1c; Prediabetic State
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