title: Postchallenge glucose, A1C, and fasting glucose as predictors of type 2 diabetes and cardiovascular disease: a 10-year prospective cohort study.
abstract: OBJECTIVE
  A1C has been proposed as a new indicator for high risk of type 2 diabetes. The long-term predictive power and comparability of elevated A1C with the currently used high-risk indicators remain unclear. We assessed A1C, impaired glucose tolerance (IGT), and impaired fasting glucose (IFG) as predictors of type 2 diabetes and cardiovascular disease (CVD) at 10 years.
  
  
  METHODS
  This prospective population-based study of 593 inhabitants from northern Finland, born in 1935, was conducted between 1996 and 2008. An oral glucose tolerance test (OGTT) was conducted at baseline and follow-up, and A1C was determined at baseline. Those with a history of diabetes were excluded from the study. Elevated A1C was defined as 5.7-6.4%. Incident type 2 diabetes was confirmed by two OGTTs. Cardiovascular outcome was measured as incident CVD or CVD mortality. Multivariate log-binomial regression models were used to predict diabetes, CVD, and CVD mortality at 10 years. Receiver operating characteristic curves compared predictive values of A1C, IGT, and IFG.
  
  
  RESULTS
  Incidence of diabetes during the follow-up was 17.1%. Two of three of the cases of newly diagnosed diabetes were predicted by a raise in >or=1 of the markers. Elevated A1C, IGT, or IFG preceded diabetes in 32.8, 40.6, and 21.9%, respectively. CVD was predicted by an intermediate and diabetic range of 2-h glucose but only by diabetic A1C levels in women.
  
  
  CONCLUSIONS
  A1C predicted 10-year risk of type 2 diabetes at a range of A1C 5.7-6.4% but CVD only in women at A1C >or=6.5%.
authors.affiliation: Institute of Health Sciences, Faculty of Medicine, University of Oulu, Oulu, Finland. henna.cederberg@oulu.fi
authors.forename: Henna
authors.initials: H
authors.lastname: Cederberg
authors.forename: Tuula
authors.initials: T
authors.lastname: Saukkonen
authors.forename: Mauri
authors.initials: M
authors.lastname: Laakso
authors.forename: Jari
authors.initials: J
authors.lastname: Jokelainen
authors.forename: Pirjo
authors.initials: P
authors.lastname: Härkönen
authors.forename: Markku
authors.initials: M
authors.lastname: Timonen
authors.forename: Sirkka
authors.initials: S
authors.lastname: Keinänen-Kiukaanniemi
authors.forename: Ulla
authors.initials: U
authors.lastname: Rajala
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism; D005215:Fasting / Q000097:blood*; D018149:Glucose Intolerance / Q000378:metabolism*; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D011446:Prospective Studies
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin