title: Twenty year fitness trends in young adults and incidence of prediabetes and diabetes: the CARDIA study.
abstract: The prospective association between cardiorespiratory fitness (CRF) measured in young adulthood and middle age on development of prediabetes, defined as impaired fasting glucose and/or impaired glucose tolerance, or diabetes by middle age remains unknown. We hypothesised that higher fitness levels would be associated with reduced risk for developing incident prediabetes/diabetes by middle age.
  
  
  
  Participants were from the Coronary Artery Risk Development in Young Adults (CARDIA) study who were free from prediabetes/diabetes at baseline (year 0 [Y0]: 1985-1986). CRF was quantified by treadmill duration (converted to metabolic equivalents [METs]) at Y0, Y7 and Y20 and prediabetes/diabetes status was assessed at Y0, Y7, Y10, Y15, Y20 and Y25. We use an extended Cox model with CRF as the primary time-varying exposure. BMI was included as a time-varying covariate. The outcome was development of either prediabetes or diabetes after Y0. Model 1 included age, race, sex, field centre, CRF and BMI. Model 2 additionally included baseline (Y0) smoking, energy intake, alcohol intake, education, systolic BP, BP medication use and lipid profile.
  
  
  
  Higher fitness was associated with lower risk for developing incident prediabetes/diabetes (difference of 1 MET: HR 0.99898 [95% CI 0.99861, 0.99940], p < 0.01), which persisted (difference of 1 MET: HR 0.99872 [95% CI 0.99840, 0.99904], p < 0.01] when adjusting for covariates.
  
  
  
  Examining participants who had fitness measured from young adulthood to middle age, we found that fitness was associated with lower risk for developing prediabetes/diabetes, even when adjusting for BMI over this time period. These findings emphasise the importance of fitness in reducing the health burden of prediabetes and diabetes.
authors.affiliation: Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, MMC 101, 420 Delaware St SE, Minneapolis, MN, 55455, USA. chow0007@umn.edu.
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Chow
authors.affiliation: Department of Epidemiology, University of California Irvine, Irvine, CA, USA.
authors.forename: Andrew O
authors.initials: AO
authors.lastname: Odegaard
authors.affiliation: Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, MMC 101, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
authors.forename: Tyler A
authors.initials: TA
authors.lastname: Bosch
authors.affiliation: Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, MMC 101, 420 Delaware St SE, Minneapolis, MN, 55455, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Bantle
authors.affiliation: Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: John
authors.initials: J
authors.lastname: Hughes
authors.affiliation: Department of Preventive Medicine, Northwestern University, Chicago, IL, USA.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Carnethon
authors.affiliation: Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA.
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Ingram
authors.affiliation: Department of Pediatrics, University of Alabama, Birmingham, AL, USA.
authors.forename: Nefertiti
authors.initials: N
authors.lastname: Durant
authors.affiliation: Department of Preventive Medicine, University of Alabama, Birmingham, AL, USA.
authors.forename: Cora E
authors.initials: CE
authors.lastname: Lewis
authors.affiliation: Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Ryder
authors.affiliation: Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Shay
authors.affiliation: Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Kelly
authors.affiliation: Division of Epidemiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Schreiner
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015337:Multicenter Studies as Topic; D010809:Physical Fitness / Q000502:physiology*; D011236:Prediabetic State / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Cardiorespiratory fitness; Diabetes; Prediabetes