title: Confirming glycemic status in the Diabetes Prevention Program: implications for diagnosing diabetes in high risk adults.
abstract: OBJECTIVE
  To examine the ability of fasting plasma glucose (FPG) and/or 2-h glucose to confirm diabetes and to determine the proportion of participants with HbA1c ≥6.5%.
  
  
  METHODS
  Diabetes confirmation rates were calculated after a single elevated FPG and/or 2-h glucose on an oral glucose tolerance test (OGTT) using a confirmatory OGTT performed within 6 weeks.
  
  
  RESULTS
  772 (24%) participants had elevated FPG or 2-h glucose on an OGTT that triggered a confirmation visit. There were 101 triggers on FPG alone, 574 on 2-h glucose alone, and 97 on both. Only 47% of participants who triggered had confirmed diabetes. While the confirmation rate for FPG was higher than that for 2-h glucose, the larger number of 2-h glucose triggers resulted in 87% of confirmed cases triggering on 2-h glucose. Confirmation rates increased to 75% among persons with FPG ≥126 mg/dl and HbA1c ≥6.5%.
  
  
  CONCLUSIONS
  Only half of the persons with elevated FPG and IGT were subsequently confirmed to have diabetes. At current diagnostic levels, more persons trigger on 2-h glucose than on FPG, but fewer of these persons have their diagnoses confirmed. In individuals with FPG ≥126 mg/dl and HbA1c ≥6.5%, the confirmation rate was increased.
authors.affiliation: Biostatistics Center, George Washington University, Rockville, MD, USA. dppmail@bsc.gwu.edu
authors.forename: C A
authors.initials: CA
authors.lastname: Christophi
authors.forename: H E
authors.initials: HE
authors.lastname: Resnick
authors.forename: R E
authors.initials: RE
authors.lastname: Ratner
authors.forename: M
authors.initials: M
authors.lastname: Temprosa
authors.forename: S
authors.initials: S
authors.lastname: Fowler
authors.forename: W C
authors.initials: WC
authors.lastname: Knowler
authors.forename: H
authors.initials: H
authors.lastname: Shamoon
authors.forename: E
authors.initials: E
authors.lastname: Barrett-Connor
authors.forename: S E
authors.initials: SE
authors.lastname: Kahn
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D005215:Fasting / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology* / Q000517:prevention & control; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D012306:Risk
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human