title: Long-term repeatability of measures of early insulin secretion derived from an intravenous glucose tolerance test and conversion from impaired glucose tolerance to diabetes.
abstract: OBJECTIVE
  We assessed the long-term repeatability of the acute insulin response (AIR) and sensitivity index (S(I)) derived from the frequently sampled intravenous glucose tolerance test (FSIGT).
  
  
  METHODS
  An FSIGT was performed in 20 women who participated in a 6.5-month rye- and wheat-bread intervention trial, 70 men and women with impaired fasting glycaemia (IFG) or impaired glucose tolerance (IGT) who participated in the Genobin study, and 81 men and women with IGT who participated in the Finnish Diabetes Prevention Study (DPS).
  
  
  RESULTS
  The correlation of AIR and S(I) at base-line with respective values after the 6.5-8.5-month trials was 0.86-0.88 and 0.71-0.84, and before and after 4 years in the DPS substudy, 0.86 and 0.53. In multivariate analyses, AIR (relative risk for a 1-SD change, 0.67; 95% confidence intervals 0.46-0.97) predicted the conversion from IGT to diabetes in the DPS substudy.
  
  
  CONCLUSIONS
  AIR is highly repeatable even after 4 years of follow-up. The long-term repeatability of S(I) is moderate. Our findings emphasize the importance of impaired early insulin secretion in the transition from IGT to diabetes, and the high degree of tracking of measures of early insulin secretion derived from the FSIGT.
authors.affiliation: Department of Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: David E
authors.initials: DE
authors.lastname: Laaksonen
authors.forename: Leo
authors.initials: L
authors.lastname: Niskanen
authors.forename: Hannu
authors.initials: H
authors.lastname: Mykkänen
authors.forename: Katri S
authors.initials: KS
authors.lastname: Juntunen
authors.forename: Ursula
authors.initials: U
authors.lastname: Schwab
authors.forename: Marjukka
authors.initials: M
authors.lastname: Kolehmainen
authors.forename: Rainer
authors.initials: R
authors.lastname: Rauramaa
authors.forename: Jaakko
authors.initials: J
authors.lastname: Tuomilehto
authors.forename: Matti
authors.initials: M
authors.lastname: Uusitupa
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D016001:Confidence Intervals; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000503:physiopathology*; D005215:Fasting; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D018149:Glucose Intolerance; D005951:Glucose Tolerance Test / Q000379:methods*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D007328:Insulin