title: Self-reported physical activity is associated with β-cell function in Mexican American adults.
abstract: OBJECTIVE
  To examine the association between self-reported physical activity (PA) and diabetes-related quantitative traits.
  
  
  METHODS
  The observational cohort was 1,152 Mexican American adults with dual-energy X-ray absorptiometry, oral and intravenous glucose tolerance tests, and self-reported dietary and PA questionnaires. PA was categorized into three mutually exclusive groups according to the U.S. Department of Health and Human Services PA guidelines for Americans: low (vigorous <75 min/week and moderate <150 min/week), moderate (vigorous ≥75 min/week or moderate ≥150 min/week), and high (vigorous ≥75 min/week and moderate ≥150 min/week). Trends in PA groups were tested for association with metabolic traits in a cross-sectional analysis.
  
  
  RESULTS
  The participants' mean age was 35 years (range, 18-66 years), mean BMI was 29.6 kg/m(2), and 73% were female. Among them, 501 (43%), 448 (39%), and 203 (18%) were classified as having low, moderate, and high PA, respectively. After adjustment for age, a higher PA was significantly associated with lower 2-h glucose, fasting insulin, and 2-h insulin and greater β-cell function (P = 0.001, 0.0003, 0.0001, and 0.004, respectively). The association did not differ significantly by sex. Results were similar after further adjustment for age, sex, BMI, or percent body fat.
  
  
  CONCLUSIONS
  An increasing level of PA is associated with a better glucose and insulin profile and enhanced β-cell function that is not explained by differences in BMI or percent body fat. Our results suggest that PA can be beneficial to β-cell function and glucose regulation independent of obesity.
authors.affiliation: Division of Biostatistics, Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Zhanghua
authors.initials: Z
authors.lastname: Chen
authors.forename: Mary Helen
authors.initials: MH
authors.lastname: Black
authors.forename: Richard M
authors.initials: RM
authors.lastname: Watanabe
authors.forename: Enrique
authors.initials: E
authors.lastname: Trigo
authors.forename: Miwa
authors.initials: M
authors.lastname: Takayanagi
authors.forename: Jean M
authors.initials: JM
authors.lastname: Lawrence
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Buchanan
authors.forename: Anny H
authors.initials: AH
authors.lastname: Xiang
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D017058:Mexican Americans; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin