title: Decreased Glycemic Difference Between Diabetes and Nondiabetes in the Elderly Leads to the Reduced Diagnostic Accuracy of Hemoglobin A1c for Diabetes Screening in an Aged Chinese Population.
abstract: BACKGROUND
  This study investigated the impact of age on the accuracy of glycated hemoglobin (HbA1c) for diabetes screening and explored the possible cause(s).
  
  
  METHODS
  Data from 3,050 Chinese participants 25-75 years of age without known diabetes in a population-based cross-sectional survey were analyzed. Diabetes was diagnosed by the oral glucose tolerance test (OGTT). The performance of HbA1c for detecting OGTT-defined diabetes in tertile groups (divided by age) was evaluated by the area under the curve (AUC) of the receiver operating characteristic curve (ROC). The effect of age on the difference in glucose levels between participants with and without diabetes and the impact of this difference on the performance of HbA1c were evaluated.
  
  
  RESULTS
  In young (25-41 years old), middle-aged (41-53 years old), and old (55-72 years old) participants, the ROC AUC (95% confidence interval) of HbA1c for detecting OGTT-defined diabetes was 0.958 (0.915, 1.000), 0.891 (0.852, 0.930), and 0.861 (0.821, 0.901), respectively (P = 0.005). The difference of fasting plasma glucose between participants with diabetes and those without diabetes decreased with increasing age: 3.01 (2.80, 3.22) mmol/L, 2.90 (2.71, 3.09) mmol/L, and 2.33 (2.16, 2.50) mmol/L in the three consecutive age groups, respectively. A similar pattern was found in 2-h postprandial plasma glucose. The impact of age on the diagnostic power of HbA1c diminished after data were rearranged to artificially increase the difference between participants without diabetes and those with diabetes.
  
  
  CONCLUSIONS
  The accuracy of HbA1c for detecting OGTT-defined diabetes declines with age. This is largely due to the decreased separation in glycemic levels between participants with diabetes and without diabetes in the elderly.
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Xiantong
authors.initials: X
authors.lastname: Zou
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .|2 Department of Endocrinology and Metabolism, Pinggu Hospital , Beijing, China .
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Li
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Cai
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Simin
authors.initials: S
authors.lastname: Zhang
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Xiuying
authors.initials: X
authors.lastname: Zhang
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Xueyao
authors.initials: X
authors.lastname: Han
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Xianghai
authors.initials: X
authors.lastname: Zhou
authors.affiliation: 1 Department of Endocrinology and Metabolism, Peking University People's Hospital , Beijing, China .
authors.forename: Linong
authors.initials: L
authors.lastname: Ji
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D001786:Blood Glucose / Q000032:analysis; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D003951:Diagnostic Errors; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006306:Health Surveys; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009749:Nutrition Surveys; D019518:Postprandial Period; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D015995:Prevalence; D012372:ROC Curve
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human