title: Applicability of a combination of hemoglobin A(1c)  and fasting plasma glucose in population-based prediabetes screening.
abstract: BACKGROUND
  The purpose of this study is to determine: (i) the concordance between a combination of hemoglobin A(1c) (Hb(A1c)) and fasting plasma glucose (FPG) (Hb(A1c) + FPG) and a combination of FPG and 2-h plasma glucose (2hPG) (FPG + 2hPG); and (ii) whether substituting FPG + 2hPG with Hb(A1c) + FPG can enhance the detection of prediabetes in diabetes-free non-Hispanic Whites, non-Hispanic Blacks, and Mexican-Americans adults.
  
  
  METHODS
  Data (n = 1376) from the 2007 to 2008 U.S. National Health and Nutrition Examination Surveys were used for this investigation. Prediabetes cut points were determined using 5.7-6.4%, 100-125, and 140-199 mg/dL for Hb(A1c), FPG, and 2hPG, respectively. Concordances between Hb(A1c) and FPG, Hb(A1c) and 2hPG, Hb(A1c) + FPG and FPG + 2hPG in screening for undiagnosed prediabetes were determined using sensitivity, specificity, and positive and negative likelihood ratios.
  
  
  RESULTS
  The overall concordance between Hb(A1c) + FPG and FPG + 2hPG in screening for prediabetes was high, as indicated by a sensitivity of 92.4% (95% CI = 90.5-94.5) and specificity of 84.1% (81.2-87.0). The application of Hb(A1c) + FPG was associated with a higher prevalence of prediabetes compared to FPG + 2hPG. Compared with FPG + 2hPG, screening with Hb(A1c) + FPG was associated with 3.2%, 24.3%, and 4.2% relative increases in the identification of prediabetes in nondiabetic non-Hispanic Whites, non-Hispanic Blacks and Mexican-Americans, respectively.
  
  
  CONCLUSIONS
  The enhanced prevalence of prediabetes using Hb(A1c) + FPG compared with FPG + 2hPG calls for the need to redefine at a more basic and practical level how to apply Hb(A1c) in screening for prediabetes. A redefined Hb(A1c) that incorporates FPG, age, race/ethnicity, and body mass index may be a better way to use Hb(A1c) in population-based and clinical settings.
authors.affiliation: Institute of Public Health, Georgia State University, Atlanta, Georgia 30303, USA. iokosun@gsu.edu
authors.forename: Ike S
authors.initials: IS
authors.lastname: Okosun
authors.forename: Monique
authors.initials: M
authors.lastname: Davis-Smith
authors.forename: J
authors.initials: J
authors.lastname: Paul Seale
authors.forename: John
authors.initials: J
authors.lastname: Ngulefac
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis*; D005006:Ethnicity; D005215:Fasting; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis*; D015995:Prevalence
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin