title: A Fit-Fat Index for Predicting Incident Diabetes in Apparently Healthy Men: A Prospective Cohort Study.
abstract: BACKGROUND
  The purpose of this study was to examine the impact of combined cardiorespiratory fitness and waist-to-height ratio in the form of a fit-fat index on incident diabetes risk. Additionally, the independent predictive performance of cardiorespiratory fitness, waist-to-height ratio, and body mass index also were estimated and compared.
  
  
  METHODS
  This was a prospective cohort study of 10,381 men who had a normal electrocardiogram and no history of major chronic disease at baseline from 1979 to 2005. Random survival forest models and traditional Cox proportional hazards models were used to predict diabetes at 5-, 10-, and 15-year incidence horizons.
  
  
  RESULTS
  Overall, 4.8% of the participants developed diabetes. Receiver operating characteristic curve analyses for incidence risk demonstrated good discrimination using random survival forest models across fitness and fatness measures; Cox models were poor to fair. The differences between fitness and fatness measures across horizons were clinically negligible. Smoothed random survival forest estimates demonstrated the impact of each fitness and fatness measure on incident diabetes was intuitive and graded.
  
  
  CONCLUSIONS
  Although fitness and fatness measures showed a similar discriminative ability in predicting incident diabetes, unique to the study was the ability of the fit-fat index to demonstrate a better indication of incident risk when compared to fitness or fatness alone. A single index combining cardiorespiratory fitness and waist-to-height ratio may be more useful because it can indicate improvements in either or both of the measures.
authors.affiliation: Kagoshima University, Graduate Medical and Dental School, Department of Psychosomatic Internal Medicine, Kagoshima, Japan.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sloan
authors.affiliation: Georgia Institute of Technology, H. Milton Stewart School of Industrial and Systems Engineering, Atlanta, Georgia, United States of America.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Haaland
authors.affiliation: National Institute of Biomedical Innovation, Health and Nutrition, Department of Health Promotion and Exercise, Tokyo, Japan.
authors.forename: Susumu S
authors.initials: SS
authors.lastname: Sawada
authors.affiliation: Harvard University, Harvard T.H. Chan School of Public Health, Department of Epidemiology, Division of Preventive Medicine, Department of Medicine, and Brigham and Women's Hospital and Harvard Medical School, Boston and Cambridge, Massachusetts, United States of America.
authors.forename: I-Min
authors.initials: IM
authors.lastname: Lee
authors.affiliation: University of South Carolina, Arnold School of Public Health, Department of Exercise Science, Columbia, South Carolina, United States of America.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Sui
authors.affiliation: Iowa State University, College of Human Sciences, Department of Kinesiology, Ames, Iowa, United States of America.
authors.forename: Duck-Chul
authors.initials: DC
authors.lastname: Lee
authors.affiliation: Georgia Institute of Technology, H. Milton Stewart School of Industrial and Systems Engineering, Atlanta, Georgia, United States of America.
authors.forename: Yassine
authors.initials: Y
authors.lastname: Ridouane
authors.affiliation: National University of Singapore, Saw Swee Hock School of Public Health, Singapore.
authors.forename: Falk
authors.initials: F
authors.lastname: Müller-Riemenschneider
authors.affiliation: University of South Carolina, Arnold School of Public Health, Department of Exercise Science, Columbia, South Carolina, United States of America.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D000328:Adult; D019540:Area Under Curve; D000072599:Cardiorespiratory Fitness; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000401:mortality; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D065927:Waist-Height Ratio