title: The usefulness of glycated hemoglobin A1c (HbA1c) for identifying dysglycemic states in individuals without previously diagnosed diabetes.
abstract: OBJECTIVE
  We investigated HbA1c's validity as a screening parameter for excluding dysglycemic states in the studied population.
  
  
  METHODS
  Sensitivity and specificity of HbA1c in some cut-off points were compared with diagnoses based on the oral glucose tolerance test (OGTT) in individuals diagnosed between 2009-2010. Receiver operating characteristic (ROC) analysis for HbA1c was conducted. HbA1c and OGGT measures were done in 441 people (253 women, 187 men, average age 40.1 years (18-79 years)). Based on the OGGT test 37 individuals were diagnosed as diabetic, 28 as impaired glucose tolerant (IGT) and 63 as having impaired fasting glycemia (IFG).
  
  
  RESULTS
  A cut-off value of 6.5% HbA1c classifies diabetic subjects with a sensitivity of 45.9% and specificity of 97.5%. In the investigated population the best cut-off point (the highest sum of the sensitivity and specificity) was 5.9% HbA1c (sensitivity 86.6%, specificity 73%). HbA1c values excluding the risk of dysglycemic states have shown false negative rate in 31.9% when HbA1c was 5.5% and 10.6% when HbA1c was 5.0%.
  
  
  CONCLUSIONS
  Our results indicate that in the investigated population the evaluation of the prevalence of type 2 diabetes using HbA1c values proposed by the American Diabetes Association (ADA) has unsatisfactory sensitivity and detects less than a half of cases of diabetes based on the OGTT diagnoses. HbA1c 5.7% does not have sufficient specificity to identify individuals not being at risk of any disorder of glucose metabolism.
authors.affiliation: Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Poland. edyta.adamska@umb.edu.pl
authors.forename: E
authors.initials: E
authors.lastname: Adamska
authors.forename: M
authors.initials: M
authors.lastname: Waszczeniuk
authors.forename: J
authors.initials: J
authors.lastname: Gościk
authors.forename: A
authors.initials: A
authors.lastname: Golonko
authors.forename: J
authors.initials: J
authors.lastname: Wilk
authors.forename: J
authors.initials: J
authors.lastname: Pliszka
authors.forename: K
authors.initials: K
authors.lastname: Maliszewska
authors.forename: D
authors.initials: D
authors.lastname: Lipińska
authors.forename: R
authors.initials: R
authors.lastname: Milewski
authors.forename: A
authors.initials: A
authors.lastname: Wasilewska
authors.forename: A
authors.initials: A
authors.lastname: Citko
authors.forename: A
authors.initials: A
authors.lastname: Nikołajuk
authors.forename: L
authors.initials: L
authors.lastname: Ostrowska
authors.forename: A
authors.initials: A
authors.lastname: Krętowski
authors.forename: M
authors.initials: M
authors.lastname: Górska
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000097:blood* / Q000175:diagnosis*; D005188:False Negative Reactions; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human