title: Long-term trends in cardiorespiratory fitness and the incidence of type 2 diabetes.
abstract: OBJECTIVE
  Whereas single assessments of cardiorespiratory fitness have been shown to predict lower incidence of type 2 diabetes, there are no data on long-term trends in fitness and risk. We investigated the relationship between long-term trends in fitness and the incidence of type 2 diabetes.
  
  
  METHODS
  A cohort of 4,187 Japanese men free of diabetes completed annual health checkups and fitness tests for estimated maximal oxygen uptake at least four times over 7 years (1979-1985). We modeled the trend in fitness over 7 years for each man using simple linear regression. Men were then divided into quartiles based on the regression coefficient (slope) from the model. During the follow-up period (1985-1999), 274 men developed diabetes. Hazard ratios (HRs) and 95% CIs for the incidence of diabetes were obtained using the Cox proportional hazards model.
  
  
  RESULTS
  Men in the lowest quartile of the distribution decreased in fitness over the 7 years (median slope -1.25 ml/kg/min), whereas men in the highest quartile increased in fitness (median slope 1.33 ml/kg/min). With adjustment for age, initial fitness level, BMI, systolic blood pressure, cigarette smoking, alcohol intake, and a family history of diabetes and use of the lowest quartile, the HRs (95% CI) for the second through fourth quartiles were 0.64 (0.46-0.89), 0.40 (0.27-0.58), and 0.33 (0.21-0.50), respectively (P(trend) < 0.001).
  
  
  CONCLUSIONS
  These results indicate that the long-term trend in fitness is a strong predictor of the incidence of type 2 diabetes in Japanese men.
authors.affiliation: Health Promotion Center, Tokyo Gas Co, Tokyo, Japan. s-sawada@tokyo-gas.co.jp
authors.forename: Susumu S
authors.initials: SS
authors.lastname: Sawada
authors.forename: I-Min
authors.initials: IM
authors.lastname: Lee
authors.forename: Hisashi
authors.initials: H
authors.lastname: Naito
authors.forename: Jun
authors.initials: J
authors.lastname: Noguchi
authors.forename: Koji
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Muto
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Higaki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D000328:Adult; D000428:Alcohol Drinking; D001794:Blood Pressure; D015992:Body Mass Index; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D015994:Incidence; D016014:Linear Models; D008297:Male; D010809:Physical Fitness / Q000502:physiology*; D016016:Proportional Hazards Models; D012307:Risk Factors