title: A1C for screening and diagnosis of type 2 diabetes in routine clinical practice.
abstract: OBJECTIVE
  To evaluate A1C for screening and diagnosis of undiagnosed type 2 diabetes defined by oral glucose tolerance testing in clinical and general populations.
  
  
  METHODS
  A1C cut offs (< or =5.5% to rule out diabetes; > or =7.0% to rule in diabetes) were derived from a clinical group (Melbourne Pathology [MP] group: n = 2,494; undiagnosed diabetes 34.6%) and then evaluated in a population-based sample (AusDiab group: n = 6,015; undiagnosed diabetes 4.6%).
  
  
  RESULTS
  For diabetes in the MP and AusDiab groups, A1C at 5.5% gave sensitivities of 98.7 and 83.5%, while A1C at 7.0% gave specificities of 98.2 and 100%, respectively. Many (61.9-69.3%) with impaired A1C (5.6-6.9%) in both populations had abnormal glucose status.
  
  
  CONCLUSIONS
  A1C < or =5.5% and > or =7.0% predicts absence or presence of type 2 diabetes, respectively, while at A1C 6.5-6.9% diabetes is highly probable in clinical and population settings. A high proportion of people with impaired A1C have abnormal glucose status requiring follow-up.
authors.affiliation: Melbourne Pathology Services, Melbourne, Australia. zhong.lu@mps.com.au
authors.forename: Zhong X
authors.initials: ZX
authors.lastname: Lu
authors.forename: Karen Z
authors.initials: KZ
authors.lastname: Walker
authors.forename: Kerin
authors.initials: K
authors.lastname: O'Dea
authors.forename: Ken A
authors.initials: KA
authors.lastname: Sikaris
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Shaw
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis*; D017127:Glycation End Products, Advanced / Q000032:analysis*; D006801:Humans
chemical_list: D017127:Glycation End Products, Advanced